Separate test_numeric_compat into method-specific tests
A more reasonably-scoped attempt at #19255.

- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19321?src=pr&el=h1) Report
> Merging [#19321](https://codecov.io/gh/pandas-dev/pandas/pull/19321?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/1245f0673074316b53d1d1ee10abd6077058b133?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/19321/graphs/tree.svg?width=650&height=150&src=pr&token=eZ4WkYLtcO)](https://codecov.io/gh/pandas-dev/pandas/pull/19321?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #19321   +/-   ##
=======================================
  Coverage   91.53%   91.53%           
=======================================
  Files         150      150           
  Lines       48739    48739           
=======================================
  Hits        44612    44612           
  Misses       4127     4127
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.9% <ø> (ø)` | :arrow_up: |
| #single | `41.73% <ø> (ø)` | :arrow_up: |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19321?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/19321?src=pr&el=footer). Last update [1245f06...3df8a1f](https://codecov.io/gh/pandas-dev/pandas/pull/19321?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 thanks, nice scope, means merge faster :>