CLN: Remove u and u_safe from pandas.compat

[jschendel]

• xref CLN: remove PY2 #25725
• tests added / passed
• passes git diff upstream/master -u -- "*.py" | flake8 --diff

Another incremental step in removing Python 2. Only non-standard changes were to pandas/tests/test_strings.py where I deleted a bunch of code, as removing u resulted in duplicate test scenarios.

[jreback]

can we remove unicode strings themselves if they e.g. u'....'?

[jschendel]

can we remove unicode strings themselves if they e.g. u'....'?

Yeah, I was thinking that seemed better suited for a separate PR since, after a quick check, there looks to be 1000+ instances of it, and I didn't want to jam too much into a single PR. Can do it here if you'd prefer.

[codecov]

Codecov Report

Merging #25852 into master will increase coverage by 0.01%.
The diff coverage is 87.14%.

@@            Coverage Diff             @@
##           master   #25852      +/-   ##
==========================================
+ Coverage   91.45%   91.47%   +0.01%     
==========================================
  Files         172      172              
  Lines       52892    52870      -22     
==========================================
- Hits        48373    48362      -11     
+ Misses       4519     4508      -11

Flag	Coverage Δ
#multiple	90.03% <80%> (+0.01%)	⬆️
#single	41.82% <42.85%> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/compat/__init__.py	59.82% <ø> (+1.07%)	⬆️
pandas/core/panel.py	35.62% <0%> (-0.1%)	⬇️
pandas/util/testing.py	89.3% <100%> (ø)	⬆️
pandas/core/frame.py	96.79% <100%> (ø)	⬆️
pandas/io/formats/latex.py	100% <100%> (ø)	⬆️
pandas/compat/pickle_compat.py	75.6% <100%> (ø)	⬆️
pandas/core/strings.py	98.59% <100%> (ø)	⬆️
pandas/io/json/json.py	93.22% <100%> (ø)	⬆️
pandas/core/indexes/base.py	96.57% <100%> (ø)	⬆️
pandas/core/arrays/categorical.py	95.96% <100%> (ø)	⬆️
... and 10 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
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[codecov]

Codecov Report

Merging #25852 into master will increase coverage by 0.01%.
The diff coverage is 87.14%.

@@            Coverage Diff             @@
##           master   #25852      +/-   ##
==========================================
+ Coverage   91.45%   91.47%   +0.01%     
==========================================
  Files         172      172              
  Lines       52892    52870      -22     
==========================================
- Hits        48373    48362      -11     
+ Misses       4519     4508      -11

Flag	Coverage Δ
#multiple	90.03% <80%> (+0.01%)	⬆️
#single	41.82% <42.85%> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/compat/__init__.py	59.82% <ø> (+1.07%)	⬆️
pandas/core/panel.py	35.62% <0%> (-0.1%)	⬇️
pandas/util/testing.py	89.3% <100%> (ø)	⬆️
pandas/core/frame.py	96.79% <100%> (ø)	⬆️
pandas/io/formats/latex.py	100% <100%> (ø)	⬆️
pandas/compat/pickle_compat.py	75.6% <100%> (ø)	⬆️
pandas/core/strings.py	98.59% <100%> (ø)	⬆️
pandas/io/json/json.py	93.22% <100%> (ø)	⬆️
pandas/core/indexes/base.py	96.57% <100%> (ø)	⬆️
pandas/core/arrays/categorical.py	95.96% <100%> (ø)	⬆️
... and 10 more

---

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 6e0f9a9...8c68c28. Read the comment docs.

[jreback]

separate is good!

[WillAyd]

lgtm - thanks @jschendel that was a lot!

[WillAyd]

surprise this wasn't a lint error before

[jreback]

thanks @jschendel keep em coming!