Suppress incorrect warning in nargsort for timezone-aware DatetimeIndex
Closes #25439, alternative to https://github.com/pandas-dev/pandas/pull/25595 for 0.24.2
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25629?src=pr&el=h1) Report
> Merging [#25629](https://codecov.io/gh/pandas-dev/pandas/pull/25629?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/e28ae70ba8bd8b4174143543d1660421bc67887b?src=pr&el=desc) will **increase** coverage by `<.01%`.
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/25629/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25629?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #25629      +/-   ##
==========================================
+ Coverage   91.26%   91.26%   +<.01%     
==========================================
  Files         173      173              
  Lines       52968    52971       +3     
==========================================
+ Hits        48339    48342       +3     
  Misses       4629     4629
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.83% <100%> (ø)` | :arrow_up: |
| #single | `41.71% <100%> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/25629?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/sorting.py](https://codecov.io/gh/pandas-dev/pandas/pull/25629/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc29ydGluZy5weQ==) | `98.29% <100%> (+0.02%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25629?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/25629?src=pr&el=footer). Last update [e28ae70...cd11341](https://codecov.io/gh/pandas-dev/pandas/pull/25629?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/25629?src=pr&el=h1) Report
> Merging [#25629](https://codecov.io/gh/pandas-dev/pandas/pull/25629?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/e28ae70ba8bd8b4174143543d1660421bc67887b?src=pr&el=desc) will **increase** coverage by `<.01%`.
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/25629/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25629?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #25629      +/-   ##
==========================================
+ Coverage   91.26%   91.26%   +<.01%     
==========================================
  Files         173      173              
  Lines       52968    52971       +3     
==========================================
+ Hits        48339    48342       +3     
  Misses       4629     4629
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.83% <100%> (ø)` | :arrow_up: |
| #single | `41.71% <100%> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/25629?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/sorting.py](https://codecov.io/gh/pandas-dev/pandas/pull/25629/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc29ydGluZy5weQ==) | `98.29% <100%> (+0.02%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25629?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/25629?src=pr&el=footer). Last update [e28ae70...cd11341](https://codecov.io/gh/pandas-dev/pandas/pull/25629?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

```
$ git checkout 0.24.x
$ git pull
```

2. Cherry pick the first parent branch of the this PR on top of the older branch:
```
$ git cherry-pick -m1 de52d0b10c28318ae48390dbe7abcd1807a1154a
```

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

```
$ git commit -am 'Backport PR #25629: Suppress incorrect warning in nargsort for timezone-aware DatetimeIndex'
```

4. Push to a named branch :

```
git push YOURFORK 0.24.x:auto-backport-of-pr-25629-on-0.24.x
```

5. Create a PR against branch 0.24.x, I would have named this PR:

> "Backport PR #25629 on branch 0.24.x"

And apply the correct labels and milestones.

Congratulation you did some good work ! Hopefully your backport PR will be tested by the continuous integration and merged soon!

If these instruction are inaccurate, feel free to [suggest an improvement](https://github.com/MeeseeksBox/MeeseeksDev).
                 I'll put up a backport PR for this.