Fix import format tests/indexes/ "Part One"

[thoo]

• xref Fix import formatting using isort #23334
• tests added / passed
• passes git diff upstream/master -u -- "*.py" | flake8 --diff
  Run isort -rc pandas/tests/indexes/

PR is capped at 20 files. So this is not all the files modified from pandas/tests/indexes/. So this is Part One of this directory pandas/tests/indexes/.

[pep8speaks]

Hello @thoo! Thanks for submitting the PR.

• There are no PEP8 issues in the file pandas/tests/extension/base/methods.py !

• There are no PEP8 issues in the file pandas/tests/extension/test_categorical.py !

• There are no PEP8 issues in the file pandas/tests/extension/test_interval.py !

• There are no PEP8 issues in the file pandas/tests/extension/test_sparse.py !

• There are no PEP8 issues in the file pandas/tests/indexes/interval/test_astype.py !

• There are no PEP8 issues in the file pandas/tests/indexes/interval/test_construction.py !

• There are no PEP8 issues in the file pandas/tests/indexes/interval/test_interval.py !

• There are no PEP8 issues in the file pandas/tests/indexes/interval/test_interval_new.py !

• There are no PEP8 issues in the file pandas/tests/indexes/interval/test_interval_range.py !

• There are no PEP8 issues in the file pandas/tests/indexes/interval/test_interval_tree.py !

• There are no PEP8 issues in the file pandas/tests/indexes/timedeltas/test_arithmetic.py !

• There are no PEP8 issues in the file pandas/tests/indexes/timedeltas/test_astype.py !

• There are no PEP8 issues in the file pandas/tests/indexes/timedeltas/test_construction.py !

• There are no PEP8 issues in the file pandas/tests/indexes/timedeltas/test_indexing.py !

• There are no PEP8 issues in the file pandas/tests/indexes/timedeltas/test_ops.py !

• There are no PEP8 issues in the file pandas/tests/indexes/timedeltas/test_partial_slicing.py !

• There are no PEP8 issues in the file pandas/tests/indexes/timedeltas/test_scalar_compat.py !

• There are no PEP8 issues in the file pandas/tests/indexes/timedeltas/test_setops.py !

• There are no PEP8 issues in the file pandas/tests/indexes/timedeltas/test_timedelta.py !

• There are no PEP8 issues in the file pandas/tests/indexes/timedeltas/test_timedelta_range.py !

• There are no PEP8 issues in the file pandas/tests/indexes/timedeltas/test_tools.py !

[codecov]

Codecov Report

Merging #23337 into master will decrease coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #23337      +/-   ##
==========================================
- Coverage   92.22%   92.22%   -0.01%     
==========================================
  Files         169      169              
  Lines       51261    51259       -2     
==========================================
- Hits        47277    47273       -4     
- Misses       3984     3986       +2

Flag	Coverage Δ
#multiple	90.66% <ø> (-0.01%)	⬇️
#single	42.23% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/util/testing.py	86.64% <0%> (-0.2%)	⬇️
pandas/core/dtypes/cast.py	89.22% <0%> (-0.06%)	⬇️
pandas/core/arrays/datetimes.py	97.45% <0%> (-0.01%)	⬇️
pandas/core/groupby/ops.py	96.79% <0%> (ø)	⬆️
pandas/core/groupby/base.py	91.83% <0%> (ø)	⬆️
pandas/core/arrays/sparse.py	91.84% <0%> (ø)	⬆️
pandas/core/groupby/grouper.py	98.16% <0%> (ø)	⬆️
pandas/core/groupby/groupby.py	96.48% <0%> (ø)	⬆️
pandas/core/groupby/categorical.py	95.45% <0%> (ø)	⬆️
pandas/core/series.py	93.91% <0%> (ø)	⬆️
... and 1 more

---

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[jreback]

@thoo pls remove the fixed files from the setup.cfg as then the flaker will check.

[thoo]

Sorry. I missed that part.

[jreback]

ping on green.

[jreback]

btw, since lots of these PR's, any time you push merge in master as well.

[thoo]

@jreback Pass all checks.

[jreback]

i think this was duplicated somehow.