Clean up docstring tests

[felixwang9817]

Signed-off-by: Felix Wang wangfelix98@gmail.com

What this PR does / why we need it: The current docstring tests in FeatureStore are a bit verbose. This PR makes them more concise by moving most of the setup logic into a setup function.

Which issue(s) this PR fixes:

Fixes #

Does this PR introduce a user-facing change?:

NONE

[codecov-commenter]

Codecov Report

Merging #1778 (78fe198) into master (8ef2053) will decrease coverage by 1.30%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1778      +/-   ##
==========================================
- Coverage   84.71%   83.41%   -1.31%     
==========================================
  Files          86       87       +1     
  Lines        6308     6776     +468     
==========================================
+ Hits         5344     5652     +308     
- Misses        964     1124     +160     

Flag	Coverage Δ
integrationtests	85.12% <100.00%> (+0.46%)	⬆️
unittests	64.34% <100.00%> (+0.02%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
sdk/python/feast/feature_store.py	92.90% <ø> (-0.68%)	⬇️
sdk/python/tests/doctest/test_all.py	95.91% <100.00%> (+0.79%)	⬆️
...python/tests/integration/e2e/test_universal_e2e.py	60.60% <0.00%> (-24.76%)	⬇️
...gration/offline_store/test_historical_retrieval.py	79.51% <0.00%> (-19.55%)	⬇️
...alization/test_offline_online_store_consistency.py	82.75% <0.00%> (-17.25%)	⬇️
...tegration/feature_repos/test_repo_configuration.py	94.77% <0.00%> (-5.23%)	⬇️
sdk/python/feast/feature_view.py	87.05% <0.00%> (-0.72%)	⬇️
...ts/integration/feature_repos/universal/entities.py	100.00% <0.00%> (ø)
...tegration/feature_repos/universal/feature_views.py	100.00% <0.00%> (ø)
... and 7 more

---

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[woop]

This is awesome :)

[achals]

/lgtm

[feast-ci-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: achals, felixwang9817

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[felixwang9817]

/kind housekeeping