CLN: fix typo in ctors.SeriesDtypesConstructors setup
Our benchmark for creating an `Index` from an array of floats does so from a **2-d** array, seemingly dating from when this benchmark tested `DataFrame` creation (see https://github.com/pandas-dev/pandas/commit/04db779d4c93d286bb0ab87780a85d50ec490266#diff-408a9d5de471447a365854703ca1856dL22).

Changing this to a 1-d array has no significant impact on benchmark times while reducing setup by ~40 seconds.

Before:
```
$ time asv dev -b ctors.SeriesDtypes
· Discovering benchmarks
· Running 4 total benchmarks (1 commits * 1 environments * 4 benchmarks)
[  0.00%] ·· Benchmarking existing-py_home_chris_anaconda3_bin_python
[ 12.50%] ··· ctors.SeriesDtypesConstructors.time_dtindex_from_index_with_series        2.44±0ms
[ 25.00%] ··· ctors.SeriesDtypesConstructors.time_dtindex_from_series                   2.25±0ms
[ 37.50%] ··· ctors.SeriesDtypesConstructors.time_index_from_array_floats                760±0μs
[ 50.00%] ··· ctors.SeriesDtypesConstructors.time_index_from_array_string                942±0μs

real    0m51.040s
user    0m39.813s
sys     0m10.172s
```

After:
```
$ time asv dev -b ctors.SeriesDtypes
· Discovering benchmarks
· Running 4 total benchmarks (1 commits * 1 environments * 4 benchmarks)
[  0.00%] ·· Benchmarking existing-py_home_chris_anaconda3_bin_python
[ 12.50%] ··· ctors.SeriesDtypesConstructors.time_dtindex_from_index_with_series        2.37±0ms
[ 25.00%] ··· ctors.SeriesDtypesConstructors.time_dtindex_from_series                   2.33±0ms
[ 37.50%] ··· ctors.SeriesDtypesConstructors.time_index_from_array_floats                763±0μs
[ 50.00%] ··· ctors.SeriesDtypesConstructors.time_index_from_array_string                885±0μs

real    0m13.000s
user    0m9.031s
sys     0m3.547s
```

- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24894?src=pr&el=h1) Report
> Merging [#24894](https://codecov.io/gh/pandas-dev/pandas/pull/24894?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/2fa0835737a0e3e111e893d30ed2f25b7249fd4b?src=pr&el=desc) will **decrease** coverage by `49.49%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/24894/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/24894?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #24894      +/-   ##
==========================================
- Coverage   92.38%   42.89%   -49.5%     
==========================================
  Files         166      166              
  Lines       52413    52413              
==========================================
- Hits        48424    22483   -25941     
- Misses       3989    29930   +25941
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `?` | |
| #single | `42.89% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/24894?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/formats/latex.py](https://codecov.io/gh/pandas-dev/pandas/pull/24894/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2Zvcm1hdHMvbGF0ZXgucHk=) | `0% <0%> (-100%)` | :arrow_down: |
| [pandas/core/categorical.py](https://codecov.io/gh/pandas-dev/pandas/pull/24894/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvY2F0ZWdvcmljYWwucHk=) | `0% <0%> (-100%)` | :arrow_down: |
| [pandas/io/sas/sas\_constants.py](https://codecov.io/gh/pandas-dev/pandas/pull/24894/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL3Nhcy9zYXNfY29uc3RhbnRzLnB5) | `0% <0%> (-100%)` | :arrow_down: |
| [pandas/tseries/plotting.py](https://codecov.io/gh/pandas-dev/pandas/pull/24894/diff?src=pr&el=tree#diff-cGFuZGFzL3RzZXJpZXMvcGxvdHRpbmcucHk=) | `0% <0%> (-100%)` | :arrow_down: |
| [pandas/tseries/converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/24894/diff?src=pr&el=tree#diff-cGFuZGFzL3RzZXJpZXMvY29udmVydGVyLnB5) | `0% <0%> (-100%)` | :arrow_down: |
| [pandas/io/formats/html.py](https://codecov.io/gh/pandas-dev/pandas/pull/24894/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2Zvcm1hdHMvaHRtbC5weQ==) | `0% <0%> (-99.35%)` | :arrow_down: |
| [pandas/core/groupby/categorical.py](https://codecov.io/gh/pandas-dev/pandas/pull/24894/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ3JvdXBieS9jYXRlZ29yaWNhbC5weQ==) | `0% <0%> (-95.46%)` | :arrow_down: |
| [pandas/io/sas/sas7bdat.py](https://codecov.io/gh/pandas-dev/pandas/pull/24894/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL3Nhcy9zYXM3YmRhdC5weQ==) | `0% <0%> (-91.17%)` | :arrow_down: |
| [pandas/io/sas/sas\_xport.py](https://codecov.io/gh/pandas-dev/pandas/pull/24894/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL3Nhcy9zYXNfeHBvcnQucHk=) | `0% <0%> (-90.15%)` | :arrow_down: |
| [pandas/core/tools/numeric.py](https://codecov.io/gh/pandas-dev/pandas/pull/24894/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvdG9vbHMvbnVtZXJpYy5weQ==) | `10.44% <0%> (-89.56%)` | :arrow_down: |
| ... and [123 more](https://codecov.io/gh/pandas-dev/pandas/pull/24894/diff?src=pr&el=tree-more) | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24894?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24894?src=pr&el=footer). Last update [2fa0835...24bed43](https://codecov.io/gh/pandas-dev/pandas/pull/24894?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24894?src=pr&el=h1) Report
> Merging [#24894](https://codecov.io/gh/pandas-dev/pandas/pull/24894?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/2fa0835737a0e3e111e893d30ed2f25b7249fd4b?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/24894/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/24894?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #24894   +/-   ##
=======================================
  Coverage   92.38%   92.38%           
=======================================
  Files         166      166           
  Lines       52413    52413           
=======================================
  Hits        48424    48424           
  Misses       3989     3989
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.81% <ø> (ø)` | :arrow_up: |
| #single | `42.89% <ø> (ø)` | :arrow_up: |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24894?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24894?src=pr&el=footer). Last update [2fa0835...24bed43](https://codecov.io/gh/pandas-dev/pandas/pull/24894?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Thanks @qwhelan.