Have Categorical ops defer to DataFrame; broken off of #24282

[jbrockmendel]

• closes #xxxx
• tests added / passed
• passes git diff upstream/master -u -- "*.py" | flake8 --diff
• whatsnew entry

[jreback]

need a whatsnew note (can put with one of the other notes in ops and alignment) - does this close anything?

[codecov]

Codecov Report

Merging #24630 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master   #24630      +/-   ##
==========================================
- Coverage   92.38%   92.37%   -0.01%     
==========================================
  Files         166      166              
  Lines       52395    52395              
==========================================
- Hits        48403    48402       -1     
- Misses       3992     3993       +1

Flag	Coverage Δ
#multiple	90.8% <100%> (ø)	⬆️
#single	43% <100%> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/core/arrays/categorical.py	95.41% <100%> (ø)	⬆️
pandas/util/testing.py	88% <0%> (-0.1%)	⬇️

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[codecov]

Codecov Report

Merging #24630 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master   #24630   +/-   ##
=======================================
  Coverage   92.38%   92.38%           
=======================================
  Files         166      166           
  Lines       52395    52395           
=======================================
  Hits        48403    48403           
  Misses       3992     3992

Flag	Coverage Δ
#multiple	90.8% <100%> (ø)	⬆️
#single	43% <100%> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/core/arrays/categorical.py	95.41% <100%> (ø)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update cb31b2b...c5374a2. Read the comment docs.

[jbrockmendel]

Will add what’s new and check on issues

[jreback]

thanks!