BENCH: fix timestamp asvs
- [x] closes #18680 


appveyor error in TestDataFramePlots.test_parallel_coordinates_with_sorted_labels unrelated. # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18684?src=pr&el=h1) Report
> Merging [#18684](https://codecov.io/gh/pandas-dev/pandas/pull/18684?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/a7f6714aa24ff64b49b249d76e59ede36ef04116?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/18684/graphs/tree.svg?token=eZ4WkYLtcO&width=650&src=pr&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/18684?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #18684      +/-   ##
==========================================
+ Coverage   91.57%   91.58%   +<.01%     
==========================================
  Files         153      153              
  Lines       51257    51254       -3     
==========================================
+ Hits        46937    46939       +2     
+ Misses       4320     4315       -5
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.44% <ø> (+0.02%)` | :arrow_up: |
| #single | `40.68% <ø> (-0.12%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/18684?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/18684/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/18684/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.81% <0%> (-0.1%)` | :arrow_down: |
| [pandas/tseries/frequencies.py](https://codecov.io/gh/pandas-dev/pandas/pull/18684/diff?src=pr&el=tree#diff-cGFuZGFzL3RzZXJpZXMvZnJlcXVlbmNpZXMucHk=) | `94.02% <0%> (-0.08%)` | :arrow_down: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/18684/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `82.01% <0%> (+0.19%)` | :arrow_up: |
| [pandas/plotting/\_converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/18684/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb252ZXJ0ZXIucHk=) | `66.52% <0%> (+1.73%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18684?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/18684?src=pr&el=footer). Last update [a7f6714...44bbf40](https://codecov.io/gh/pandas-dev/pandas/pull/18684?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/18684?src=pr&el=h1) Report
> Merging [#18684](https://codecov.io/gh/pandas-dev/pandas/pull/18684?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/a7f6714aa24ff64b49b249d76e59ede36ef04116?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/18684/graphs/tree.svg?width=650&height=150&src=pr&token=eZ4WkYLtcO)](https://codecov.io/gh/pandas-dev/pandas/pull/18684?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #18684      +/-   ##
==========================================
+ Coverage   91.57%   91.57%   +<.01%     
==========================================
  Files         153      153              
  Lines       51257    51263       +6     
==========================================
+ Hits        46937    46945       +8     
+ Misses       4320     4318       -2
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.44% <ø> (+0.02%)` | :arrow_up: |
| #single | `40.69% <ø> (-0.11%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/18684?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/18684/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/util/\_test\_decorators.py](https://codecov.io/gh/pandas-dev/pandas/pull/18684/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvX3Rlc3RfZGVjb3JhdG9ycy5weQ==) | `93.33% <0%> (-1.91%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/18684/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.81% <0%> (-0.1%)` | :arrow_down: |
| [pandas/tseries/frequencies.py](https://codecov.io/gh/pandas-dev/pandas/pull/18684/diff?src=pr&el=tree#diff-cGFuZGFzL3RzZXJpZXMvZnJlcXVlbmNpZXMucHk=) | `94.02% <0%> (-0.08%)` | :arrow_down: |
| [pandas/plotting/\_converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/18684/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb252ZXJ0ZXIucHk=) | `66.52% <0%> (+1.73%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18684?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/18684?src=pr&el=footer). Last update [a7f6714...44bbf40](https://codecov.io/gh/pandas-dev/pandas/pull/18684?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Thanks! 
(I removed the sample_time, let's deal with that in a coordinated way)