BUG: Avoid AmbiguousTime or NonExistentTime Error when resampling

[mroeschke]

• closes NonExistentTimeError after Resample #19375
• closes resample gives AmbiguousTimeError when index ends on a DST boundary #10117
• tests added / passed
• passes git diff upstream/master -u -- "*.py" | flake8 --diff
• whatsnew entry

[pep8speaks]

Hello @mroeschke! Thanks for submitting the PR.

• There are no PEP8 issues in the file pandas/core/resample.py !

• There are no PEP8 issues in the file pandas/tests/test_resample.py !

[codecov]

Codecov Report

Merging #22809 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master   #22809      +/-   ##
==========================================
+ Coverage   92.18%   92.18%   +<.01%     
==========================================
  Files         169      169              
  Lines       50810    50812       +2     
==========================================
+ Hits        46839    46842       +3     
+ Misses       3971     3970       -1

Flag	Coverage Δ
#multiple	90.6% <100%> (ø)	⬆️
#single	42.37% <0%> (+0.04%)	⬆️

Impacted Files	Coverage Δ
pandas/core/resample.py	96.97% <100%> (+0.18%)	⬆️

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[jreback]

thanks @mroeschke