BUG: Fix+test timezone-preservation in DTA.repeat
Also added a whatsnew for #24265.
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24483?src=pr&el=h1) Report
> :exclamation: No coverage uploaded for pull request base (`master@aeff38d`). [Click here to learn what that means](https://docs.codecov.io/docs/error-reference#section-missing-base-commit).
> The diff coverage is `0%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/24483/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/24483?src=pr&el=tree)

```diff
@@            Coverage Diff            @@
##             master   #24483   +/-   ##
=========================================
  Coverage          ?   43.04%           
=========================================
  Files             ?      166           
  Lines             ?    52328           
  Branches          ?        0           
=========================================
  Hits              ?    22524           
  Misses            ?    29804           
  Partials          ?        0
```

| Flag | Coverage Δ | |
|---|---|---|
| #single | `43.04% <0%> (?)` | |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/24483?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/arrays/datetimelike.py](https://codecov.io/gh/pandas-dev/pandas/pull/24483/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYXJyYXlzL2RhdGV0aW1lbGlrZS5weQ==) | `46.03% <0%> (ø)` | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24483?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/24483?src=pr&el=footer). Last update [aeff38d...4741f2d](https://codecov.io/gh/pandas-dev/pandas/pull/24483?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/24483?src=pr&el=h1) Report
> Merging [#24483](https://codecov.io/gh/pandas-dev/pandas/pull/24483?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/aeff38d3301d4d31650f6624304259d0dfdbd69b?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/24483/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/24483?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #24483      +/-   ##
==========================================
+ Coverage   92.31%   92.31%   +<.01%     
==========================================
  Files         166      166              
  Lines       52335    52335              
==========================================
+ Hits        48313    48314       +1     
+ Misses       4022     4021       -1
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.73% <100%> (ø)` | :arrow_up: |
| #single | `43.04% <0%> (-0.01%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/24483?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/arrays/datetimelike.py](https://codecov.io/gh/pandas-dev/pandas/pull/24483/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYXJyYXlzL2RhdGV0aW1lbGlrZS5weQ==) | `95.66% <100%> (ø)` | :arrow_up: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/24483/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `87.84% <0%> (+0.09%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24483?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/24483?src=pr&el=footer). Last update [aeff38d...2a7a5f1](https://codecov.io/gh/pandas-dev/pandas/pull/24483?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 looks like this survived with needing rebase > looks like this survived with needing rebase

Nice.  Thanks @jbrockmendel !