TST: Clean old timezone issues PT2
- [x] closes #11679
- [x] closes #11365
- [x] closes #12064
- [x] closes #12601
- [x] closes #9243
- [x] closes #11792
- [x] closes #13051
- [x] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

xref #21491, cleaning up older timezone issues and moved the whatsnew entries in the first cleanup PR from v0.23.2 to v0.24.0 as discussed https://github.com/pandas-dev/pandas/pull/21491#discussion_r197077733

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/21612?src=pr&el=h1) Report
> Merging [#21612](https://codecov.io/gh/pandas-dev/pandas/pull/21612?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/73ab162340c7cfc461a80b037da8ecf1911906d4?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/21612/graphs/tree.svg?width=650&height=150&src=pr&token=eZ4WkYLtcO)](https://codecov.io/gh/pandas-dev/pandas/pull/21612?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #21612      +/-   ##
==========================================
+ Coverage    91.9%    91.9%   +<.01%     
==========================================
  Files         154      154              
  Lines       49555    49558       +3     
==========================================
+ Hits        45542    45545       +3     
  Misses       4013     4013
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.27% <ø> (ø)` | :arrow_up: |
| #single | `42.02% <ø> (-0.01%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/21612?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/21612/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.19% <0%> (ø)` | :arrow_up: |
| [pandas/core/indexes/interval.py](https://codecov.io/gh/pandas-dev/pandas/pull/21612/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9pbnRlcnZhbC5weQ==) | `93.16% <0%> (+0.03%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/21612?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/21612?src=pr&el=footer). Last update [73ab162...0f63b69](https://codecov.io/gh/pandas-dev/pandas/pull/21612?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Addressed your comments @jreback and all green.  thanks @mroeschke had some duplicate whatsnew entries, but fixed