Tests for fixed issues in Series[datetime64]

[jbrockmendel]

• closes Negative timedeltas for deltas > 292 years #12534, closes Series[datetime64tz] - DatetimeIndex[tz] raises ValueError #19071
• tests added / passed
• passes git diff upstream/master -u -- "*.py" | flake8 --diff
• whatsnew entry

[gfyoung]

@jbrockmendel : To properly close #12534, you should also add documentation per the discussion.

[codecov]

Codecov Report

Merging #19072 into master will decrease coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #19072      +/-   ##
==========================================
- Coverage   91.54%   91.51%   -0.03%     
==========================================
  Files         148      148              
  Lines       48804    48804              
==========================================
- Hits        44676    44664      -12     
- Misses       4128     4140      +12

Flag	Coverage Δ
#multiple	89.89% <ø> (-0.03%)	⬇️
#single	41.63% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/plotting/_converter.py	65.22% <0%> (-1.74%)	⬇️

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[jreback]

were these fixed by a previous PR? can you reference it

[jreback]

this seems like a random place to put this test. can you group with other tz type op tests?

[jbrockmendel]

Sure.

[jbrockmendel]

To properly close #12534, you should also add documentation per the discussion

@gfyoung Can you expand on what you have in mind here?

[jbrockmendel]

were these fixed by a previous PR? can you reference it

For one of the tests I know it was fixed by #19024. For the other I'm not sure when it got fixed (but certainly no later than 19024)

[jreback]

thanks, if these issues are not in the whatsnew pls add (new PR).