CLN: Move test_intersect_str_dates from tests/indexes/test_range.py to test_base.py
- [X] closes #17362
- [X] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`

It doesn't seem like `test_intersect_str_dates` has anything to do with `RangeIndex`, so I've moved it from `test_range.py` to `test_base.py`.
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17366?src=pr&el=h1) Report
> :exclamation: No coverage uploaded for pull request base (`master@36dadd7`). [Click here to learn what that means](https://docs.codecov.io/docs/error-reference#section-missing-base-commit).
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/17366/graphs/tree.svg?height=150&width=650&src=pr&token=eZ4WkYLtcO)](https://codecov.io/gh/pandas-dev/pandas/pull/17366?src=pr&el=tree)

```diff
@@            Coverage Diff            @@
##             master   #17366   +/-   ##
=========================================
  Coverage          ?   90.99%           
=========================================
  Files             ?      162           
  Lines             ?    49567           
  Branches          ?        0           
=========================================
  Hits              ?    45104           
  Misses            ?     4463           
  Partials          ?        0
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.77% <ø> (?)` | |
| #single | `40.24% <ø> (?)` | |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17366?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/17366?src=pr&el=footer). Last update [36dadd7...13ae8e7](https://codecov.io/gh/pandas-dev/pandas/pull/17366?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/17366?src=pr&el=h1) Report
> :exclamation: No coverage uploaded for pull request base (`master@36dadd7`). [Click here to learn what that means](https://docs.codecov.io/docs/error-reference#section-missing-base-commit).
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/17366/graphs/tree.svg?width=650&height=150&src=pr&token=eZ4WkYLtcO)](https://codecov.io/gh/pandas-dev/pandas/pull/17366?src=pr&el=tree)

```diff
@@            Coverage Diff            @@
##             master   #17366   +/-   ##
=========================================
  Coverage          ?   90.99%           
=========================================
  Files             ?      162           
  Lines             ?    49567           
  Branches          ?        0           
=========================================
  Hits              ?    45104           
  Misses            ?     4463           
  Partials          ?        0
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.77% <ø> (?)` | |
| #single | `40.24% <ø> (?)` | |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17366?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/17366?src=pr&el=footer). Last update [36dadd7...13ae8e7](https://codecov.io/gh/pandas-dev/pandas/pull/17366?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 thanks