Base Index Tests Cleanup Part 3
progress towards #20812

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/20931?src=pr&el=h1) Report
> Merging [#20931](https://codecov.io/gh/pandas-dev/pandas/pull/20931?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/b02c69ac7309ccf63a17471b25475bf0c0ebe3c3?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/20931/graphs/tree.svg?token=eZ4WkYLtcO&width=650&src=pr&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/20931?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #20931   +/-   ##
=======================================
  Coverage   91.81%   91.81%           
=======================================
  Files         153      153           
  Lines       49478    49478           
=======================================
  Hits        45429    45429           
  Misses       4049     4049
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.21% <ø> (ø)` | :arrow_up: |
| #single | `41.85% <ø> (ø)` | :arrow_up: |


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[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/20931?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/20931?src=pr&el=footer). Last update [b02c69a...2aae882](https://codecov.io/gh/pandas-dev/pandas/pull/20931?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 thanks !