TST: collect logical ops tests, use fixtures
Collect tests for logical ops |, &, ^.

Use fixtures in a couple of places in tests/arithmetic

Rename a couple of poorly named tests

No logic is changed, nothing is moved cross-module.
Hello @jbrockmendel! Thanks for submitting the PR.

 - There are no PEP8 issues in the file [`pandas/tests/arithmetic/test_timedelta64.py`](https://github.com/jbrockmendel/pandas/blob/342c7b45c9e6e3bda667a81ed14ec06ab1ea2c75/pandas/tests/arithmetic/test_timedelta64.py) !

 - There are no PEP8 issues in the file [`pandas/tests/frame/test_operators.py`](https://github.com/jbrockmendel/pandas/blob/342c7b45c9e6e3bda667a81ed14ec06ab1ea2c75/pandas/tests/frame/test_operators.py) !

 - There are no PEP8 issues in the file [`pandas/tests/frame/test_period.py`](https://github.com/jbrockmendel/pandas/blob/342c7b45c9e6e3bda667a81ed14ec06ab1ea2c75/pandas/tests/frame/test_period.py) !

 - There are no PEP8 issues in the file [`pandas/tests/frame/test_timeseries.py`](https://github.com/jbrockmendel/pandas/blob/342c7b45c9e6e3bda667a81ed14ec06ab1ea2c75/pandas/tests/frame/test_timeseries.py) !

 - There are no PEP8 issues in the file [`pandas/tests/series/test_operators.py`](https://github.com/jbrockmendel/pandas/blob/342c7b45c9e6e3bda667a81ed14ec06ab1ea2c75/pandas/tests/series/test_operators.py) !

 # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23029?src=pr&el=h1) Report
> Merging [#23029](https://codecov.io/gh/pandas-dev/pandas/pull/23029?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/5551bcf9d297ea8a0aeffb70b17ae6730e8abf89?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/23029/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/23029?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #23029   +/-   ##
=======================================
  Coverage   92.19%   92.19%           
=======================================
  Files         169      169           
  Lines       50835    50835           
=======================================
  Hits        46868    46868           
  Misses       3967     3967
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.61% <ø> (ø)` | :arrow_up: |
| #single | `42.35% <ø> (ø)` | :arrow_up: |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23029?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/23029?src=pr&el=footer). Last update [5551bcf...97cacc2](https://codecov.io/gh/pandas-dev/pandas/pull/23029?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 thanks!