CLN: ASV reindex
Flake8'd, utilized `param`s and simplified setup where possible. 

```
$ asv dev -b ^reindex
· Discovering benchmarks
· Running 17 total benchmarks (1 commits * 1 environments * 17 benchmarks)
[  0.00%] ·· Building for existing-py_home_matt_anaconda_envs_pandas_dev_bin_python
[  0.00%] ·· Benchmarking existing-py_home_matt_anaconda_envs_pandas_dev_bin_python
[  5.88%] ··· Running ...ex.Align.time_align_series_irregular_string      604ms
[ 11.76%] ··· Running reindex.DropDuplicates.time_frame_drop_dups            ok
[ 11.76%] ···· 
               ========= ========
                inplace          
               --------- --------
                  True    26.9ms 
                 False    24.8ms 
               ========= ========

[ 17.65%] ··· Running ...ex.DropDuplicates.time_frame_drop_dups_bool         ok
[ 17.65%] ···· 
               ========= ========
                inplace          
               --------- --------
                  True    6.48ms 
                 False    7.86ms 
               ========= ========

[ 23.53%] ··· Running ...dex.DropDuplicates.time_frame_drop_dups_int         ok
[ 23.53%] ···· 
               ========= ========
                inplace          
               --------- --------
                  True    73.2ms 
                 False    65.5ms 
               ========= ========

[ 29.41%] ··· Running reindex.DropDuplicates.time_frame_drop_dups_na         ok
[ 29.41%] ···· 
               ========= ========
                inplace          
               --------- --------
                  True    30.3ms 
                 False    29.5ms 
               ========= ========

[ 35.29%] ··· Running ...ex.DropDuplicates.time_series_drop_dups_int         ok
[ 35.29%] ···· 
               ========= ========
                inplace          
               --------- --------
                  True    1.41ms 
                 False    1.35ms 
               ========= ========

[ 41.18%] ··· Running ...DropDuplicates.time_series_drop_dups_string         ok
[ 41.18%] ···· 
               ========= ========
                inplace          
               --------- --------
                  True    1.81ms 
                 False    1.78ms 
               ========= ========

[ 47.06%] ··· Running reindex.Fillna.time_float_32                           ok
[ 47.06%] ···· 
               ========== =======
                 method          
               ---------- -------
                  pad      816μs 
                backfill   911μs 
               ========== =======

[ 52.94%] ··· Running reindex.Fillna.time_reindexed                          ok
[ 52.94%] ···· 
               ========== ========
                 method           
               ---------- --------
                  pad      1.68ms 
                backfill   1.45ms 
               ========== ========

[ 58.82%] ··· Running reindex.LevelAlign.time_align_level                29.5ms
[ 64.71%] ··· Running reindex.LevelAlign.time_reindex_level              31.3ms
[ 70.59%] ··· Running reindex.LibFastZip.time_lib_fast_zip               30.2ms
[ 76.47%] ··· Running reindex.LibFastZip.time_lib_fast_zip_fillna        35.4ms
[ 82.35%] ··· Running reindex.Reindex.time_reindex_columns               2.25ms
[ 88.24%] ··· Running reindex.Reindex.time_reindex_dates                 1.90ms
[ 94.12%] ··· Running reindex.Reindex.time_reindex_multiindex             650ms
[100.00%] ··· Running reindex.ReindexMethod.time_reindex_method              ok
[100.00%] ···· 
               ========== ========
                 method           
               ---------- --------
                  pad      7.01ms 
                backfill   6.87ms 
               ========== ========
```

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18938?src=pr&el=h1) Report
> Merging [#18938](https://codecov.io/gh/pandas-dev/pandas/pull/18938?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/cdebcf374598e9141df7dc23bc75c9528e92c004?src=pr&el=desc) will **increase** coverage by `<.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/18938/graphs/tree.svg?token=eZ4WkYLtcO&width=650&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/18938?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #18938      +/-   ##
==========================================
+ Coverage   91.59%   91.59%   +<.01%     
==========================================
  Files         150      150              
  Lines       48959    48959              
==========================================
+ Hits        44843    44845       +2     
+ Misses       4116     4114       -2
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.96% <ø> (ø)` | :arrow_up: |
| #single | `41.13% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/18938?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/18938/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `84.9% <0%> (+0.21%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18938?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/18938?src=pr&el=footer). Last update [cdebcf3...214b7e3](https://codecov.io/gh/pandas-dev/pandas/pull/18938?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 thanks, ``fillMethod`` was long ago deprecated :<