Fix 28021: Add 5% padding in timeseries line plot
- [x] closes #28021 
- [x] All code checks passed
- [x] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` (**will do this once this PR is reviewed**)
- [x] Tests passed (`pytest pandas/tests/plotting/test_datetimelike.py`)
Was hunting through commits and found https://github.com/pandas-dev/pandas/commit/3795272ad8987f5af22c5887fc95bb35c1b6bb69#diff-b742bb6314b1f7b55dd7a0987ae6102f529a8d4faa6a5524ba9122d47138ad23R393 which does the exact thing that I have done. But I don't know if this is the right way to do it because it was removed. I am new to this and would like some references to do this better. This pull request is stale because it has been open for thirty days with no activity. Please [update](https://pandas.pydata.org/pandas-docs/stable/development/contributing.html#updating-your-pull-request) and respond to this comment if you're still interested in working on this. Thanks for the pull request, but it appears to have gone stale. Additionally, I don't think adding arbitrary tolerances is a sufficient solution here. Closing but let's continue to discuss solutions in the original issue