BUG: Interval scalar arithmetic operations reset closed
- [X] closes #22313
- [X] tests added / passed
- [X] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [X] whatsnew entry

Including this with 0.24.0 for the time being; I think this would be easy to backport into 0.23.5 since this looks to be disjoint from the other interval related changes but thought it best to play it safe.
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/22331?src=pr&el=h1) Report
> Merging [#22331](https://codecov.io/gh/pandas-dev/pandas/pull/22331?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/ffae158749c9b72720a7fe3295d323082a5fe420?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/22331/graphs/tree.svg?src=pr&token=eZ4WkYLtcO&width=650&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/22331?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #22331   +/-   ##
=======================================
  Coverage   92.08%   92.08%           
=======================================
  Files         169      169           
  Lines       50706    50706           
=======================================
  Hits        46691    46691           
  Misses       4015     4015
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.49% <ø> (ø)` | :arrow_up: |
| #single | `42.33% <ø> (ø)` | :arrow_up: |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/22331?src=pr&el=continue).
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> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/22331?src=pr&el=footer). Last update [ffae158...13685dc](https://codecov.io/gh/pandas-dev/pandas/pull/22331?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
