TST: parametrize pytable test

[jbrockmendel]

This came up in troubleshooting a different branch, putting it up to trim the diff there.

Also a couple of small misc cleanups.

[codecov]

Codecov Report

Merging #27032 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master   #27032      +/-   ##
==========================================
- Coverage   91.99%   91.99%   -0.01%     
==========================================
  Files         180      180              
  Lines       50774    50774              
==========================================
- Hits        46711    46708       -3     
- Misses       4063     4066       +3

Flag	Coverage Δ
#multiple	90.63% <100%> (ø)	⬆️
#single	41.82% <0%> (-0.1%)	⬇️

Impacted Files	Coverage Δ
pandas/core/arrays/base.py	99.43% <ø> (ø)	⬆️
pandas/core/internals/managers.py	96% <ø> (ø)	⬆️
pandas/core/groupby/generic.py	89.33% <100%> (ø)	⬆️
pandas/io/gbq.py	88.88% <0%> (-11.12%)	⬇️
pandas/core/frame.py	96.89% <0%> (-0.12%)	⬇️
pandas/util/testing.py	90.94% <0%> (+0.1%)	⬆️

---

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[codecov]

Codecov Report

Merging #27032 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master   #27032      +/-   ##
==========================================
- Coverage   91.99%   91.99%   -0.01%     
==========================================
  Files         180      180              
  Lines       50774    50774              
==========================================
- Hits        46711    46708       -3     
- Misses       4063     4066       +3

Flag	Coverage Δ
#multiple	90.63% <100%> (ø)	⬆️
#single	41.82% <0%> (-0.1%)	⬇️

Impacted Files	Coverage Δ
pandas/core/arrays/base.py	99.43% <ø> (ø)	⬆️
pandas/core/internals/managers.py	96% <ø> (ø)	⬆️
pandas/core/groupby/generic.py	89.33% <100%> (ø)	⬆️
pandas/io/gbq.py	88.88% <0%> (-11.12%)	⬇️
pandas/core/frame.py	96.89% <0%> (-0.12%)	⬇️
pandas/util/testing.py	90.94% <0%> (+0.1%)	⬆️

---

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 8ea2d08...190b0c7. Read the comment docs.

[jreback]

thanks @jbrockmendel