fix(test): make test_clean_requests_after_schema_grant more idempotent

[ktmud]

SUMMARY

Fix a potential table name conflict in integration tests test_clean_requests_after_schema_grant.

Sometimes when the example database has wb_health_population's schema in another name---for example, public instead of None when in postgres (depending on how you configure SQLALCHEMY_EXAMPLES_URI), rerunning this test will fail and report "table already exists" error from here. It seems the intention of the test was to reset table.schema to its original schema, but simply assumed it used to be None. This PR makes this test more idempotent by actually changing the schema of the same table to the original schema.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

N/A

TESTING INSTRUCTIONS

Make sure CI passes.

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration (follow approval process in SIP-59)
  • Migration is atomic, supports rollback & is backwards-compatible
  • Confirm DB migration upgrade and downgrade tested
  • Runtime estimates and downtime expectations provided
• Introduces new feature or API
• Removes existing feature or API

[codecov]

Codecov Report

Merging #19625 (00137bc) into master (d52e386) will decrease coverage by 0.15%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #19625      +/-   ##
==========================================
- Coverage   66.53%   66.38%   -0.16%     
==========================================
  Files        1681     1681              
  Lines       64319    64319              
  Branches     6564     6564              
==========================================
- Hits        42793    42696      -97     
- Misses      19853    19950      +97     
  Partials     1673     1673              

Flag	Coverage Δ
hive	52.66% <ø> (ø)
mysql	?
postgres	?
presto	52.51% <ø> (ø)
python	82.07% <ø> (-0.31%)	⬇️
sqlite	81.71% <ø> (ø)
unit	47.24% <ø> (ø)

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

Impacted Files	Coverage Δ
superset/sql_validators/postgres.py	50.00% <0.00%> (-50.00%)	⬇️
superset/databases/commands/create.py	64.70% <0.00%> (-27.46%)	⬇️
superset/views/database/mixins.py	60.34% <0.00%> (-20.69%)	⬇️
superset/databases/commands/update.py	85.71% <0.00%> (-8.17%)	⬇️
superset/common/utils/dataframe_utils.py	85.71% <0.00%> (-7.15%)	⬇️
superset/databases/api.py	87.98% <0.00%> (-6.01%)	⬇️
superset/databases/schemas.py	94.42% <0.00%> (-4.09%)	⬇️
superset/db_engine_specs/mysql.py	93.97% <0.00%> (-3.62%)	⬇️
superset/reports/commands/log_prune.py	85.71% <0.00%> (-3.58%)	⬇️
superset/db_engine_specs/postgres.py	95.45% <0.00%> (-1.82%)	⬇️
... and 9 more

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[zhaoyongjie]

LGTM.