BUG: Unexpected behaviour when inserting timestamps into Series #57596
Resolution info:

**Resolution.RESO_SEC - 3 for seconds**
**Resolution.RESO_MIN - 4 for minute**

Observation:
With the previous code, when the current entry (**resolution: 4, entry: '2024-02-24 10:08'**) has a greater resolution value than the smallest amongst previous entries (in this case **resolution: 3, entry: '2024-02-24 10:2:30'**), it is shown that the key is said to exist within the list of keys within the Series even though it shouldn't. This does not happen when a smaller or equal resolution value entry is inserted into the Series.

![Screenshot from 2024-02-26 13-14-10](https://github.com/pandas-dev/pandas/assets/122815453/0ec3fc4d-4831-47ac-9c19-c8b8fdbbaea9)

Thought process:
With the previous code, if the current entry's resolution value is greater than the smallest resolution value amongst the previous entries, the *_LocIndexer._convert_to_indexer* method will only return an empty list (output of the method *labels.get_loc(key)*), which might be causing entries with larger resolution values not being inserted into the *Series* correctly.

Potential solution:
I have changed the method *_LocIndexer._convert_to_indexer* to return the key ('2024-02-24 10:08') instead of an empty list when the resolution value is greater than the smallest resolution value.


- [x] closes #57596 
- [ ] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [ ] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [ ] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [x] Added an entry in the latest `doc/source/whatsnew/v2.2.1.rst` file if fixing a bug or adding a new feature.

Thanks for the contribution @wleong1. Seems like something is wrong with this PR. I think you may want to clone pandas again, and before implementing your changes create a branch in git. If you work in the main branch, things get mixed with other changes, as I think it's the case here.

I'll close this, since you'll have to create a new PR if you work work in a different branch. Please let us know if you need help. 