TST/CLN: Remove more Panel tests
xref #25632

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25675?src=pr&el=h1) Report
> Merging [#25675](https://codecov.io/gh/pandas-dev/pandas/pull/25675?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/21769e9622630ab12bdcb480da0779eea644b04a?src=pr&el=desc) will **decrease** coverage by `0.04%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/25675/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25675?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #25675      +/-   ##
==========================================
- Coverage   91.29%   91.25%   -0.05%     
==========================================
  Files         173      173              
  Lines       52961    52961              
==========================================
- Hits        48349    48327      -22     
- Misses       4612     4634      +22
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.82% <ø> (-0.05%)` | :arrow_down: |
| #single | `41.73% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/25675?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/panel.py](https://codecov.io/gh/pandas-dev/pandas/pull/25675/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvcGFuZWwucHk=) | `35.72% <0%> (-2.85%)` | :arrow_down: |
| [pandas/core/generic.py](https://codecov.io/gh/pandas-dev/pandas/pull/25675/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ2VuZXJpYy5weQ==) | `93.51% <0%> (-0.15%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25675?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/25675?src=pr&el=footer). Last update [21769e9...f6a9da8](https://codecov.io/gh/pandas-dev/pandas/pull/25675?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/25675?src=pr&el=h1) Report
> Merging [#25675](https://codecov.io/gh/pandas-dev/pandas/pull/25675?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/26d991fc4e568432c3264151265c0a3ea9a6f133?src=pr&el=desc) will **decrease** coverage by `0.03%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/25675/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25675?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #25675      +/-   ##
==========================================
- Coverage   91.28%   91.25%   -0.04%     
==========================================
  Files         173      173              
  Lines       52965    52965              
==========================================
- Hits        48348    48331      -17     
- Misses       4617     4634      +17
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.82% <ø> (-0.04%)` | :arrow_down: |
| #single | `41.74% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/25675?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/panel.py](https://codecov.io/gh/pandas-dev/pandas/pull/25675/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvcGFuZWwucHk=) | `35.72% <0%> (-2.4%)` | :arrow_down: |
| [pandas/core/generic.py](https://codecov.io/gh/pandas-dev/pandas/pull/25675/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ2VuZXJpYy5weQ==) | `93.51% <0%> (-0.05%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25675?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/25675?src=pr&el=footer). Last update [26d991f...2628b3c](https://codecov.io/gh/pandas-dev/pandas/pull/25675?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 merged master to remove overlap with #25676 thanks!