BUG: .rolling() returns incorrect values when ts index is not nano seconds
- [X] closes #55106
- [X] closes #55026
- [X] [Tests added and passed]

The bug is referred to and fixed inside the code. It needs to be generalised. @jorisvandenbossche we need to have the first feedback if we can generalise the data type with some utils or more generally. Done during the in-person sprint check.
The test was parametrised, the rolling unit generalised and the version commit reverted :)
@jorisvandenbossche please let me know in case of any other changes Bumping off of 2.1.1. @lithomas1 This fix is also related to other subfunctions like `max`. More at https://github.com/pandas-dev/pandas/issues/55026. The PR with the related tests is available. Can you add a whatsnew note for 2.1.2? > Can you add a whatsnew note for 2.1.2?

Gladly added :) @jorisvandenbossche I have modified the validation function based on your suggestion. Tests are merged and the previous conversion has been removed. Please check it out and let me know  @jorisvandenbossche I was about to ask how is the merge on this fix going on? Anything that I can help with? Tests are failing

```
FAILED pandas/tests/window/test_rolling.py::tests_empty_df_rolling[1s] - TypeError: cannot get datetime metadata from non-datetime type
FAILED pandas/tests/window/test_timeseries_window.py::TestRollingTS::test_invalid_window_nonfixed[2MS] - AssertionError: Regex pattern did not match.
 Regex: '\\<2 \\* MonthBegins\\> is a non-fixed frequency'
 Input: 'Value must be Timedelta, string, integer, float, timedelta or convertible, not MonthBegin'
FAILED pandas/tests/window/test_timeseries_window.py::TestRollingTS::test_invalid_window_nonfixed[freq1] - AssertionError: Regex pattern did not match.
 Regex: '\\<2 \\* MonthBegins\\> is a non-fixed frequency'
 Input: 'Value must be Timedelta, string, integer, float, timedelta or convertible, not MonthBegin'
FAILED pandas/tests/window/test_timeseries_window.py::TestRollingTS::test_rolling_on_empty - TypeError: cannot get datetime metadata from non-datetime type
``` Thanks @hkhojasteh and @jorisvandenbossche  