Move tests that dont belong in test_offsets

[jbrockmendel]

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

[codecov]

Codecov Report

Merging #18747 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #18747      +/-   ##
==========================================
- Coverage   91.59%   91.57%   -0.02%     
==========================================
  Files         153      153              
  Lines       51364    51364              
==========================================
- Hits        47046    47037       -9     
- Misses       4318     4327       +9

Flag	Coverage Δ
#multiple	89.44% <ø> (ø)	⬆️
#single	40.74% <ø> (-0.12%)	⬇️

Impacted Files	Coverage Δ
pandas/io/gbq.py	25% <0%> (-58.34%)	⬇️
pandas/core/frame.py	97.81% <0%> (-0.1%)	⬇️

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[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@6a06d50). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master   #18747   +/-   ##
=========================================
  Coverage          ?   91.59%           
=========================================
  Files             ?      153           
  Lines             ?    51363           
  Branches          ?        0           
=========================================
  Hits              ?    47047           
  Misses            ?     4316           
  Partials          ?        0

Flag	Coverage Δ
#multiple	89.46% <ø> (?)
#single	40.75% <ø> (?)

---

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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[jreback]

needs a rebase, ping on green.

[jreback]

lgtm. ping on green.

[jbrockmendel]

Ping

[jreback]

thanks!