chore: Refetch samples on Explore view only when filters change

[kgabryje]

SUMMARY

This PR optimizes fetching samples. The goal is not to refetch on every change in controls panel, but only when filters change, because only filters affect the response of samples endpoint.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TEST PLAN

Verify that we refetch samples only when filters change either in Networking tab of browser console or visually, by seeing that there's no spinner that indicates fetching data.

ADDITIONAL INFORMATION

• Has associated issue: Closes [explore]only fetch View Samples data when needed #11968
• Changes UI
• Requires DB Migration.
• Confirm DB Migration upgrade and downgrade tested.
• Introduces new feature or API
• Removes existing feature or API

CC: @mistercrunch @rusackas @junlincc @adam-stasiak

[codecov-io]

Codecov Report

Merging #11999 (b5e6971) into master (38bb6f3) will decrease coverage by 3.21%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #11999      +/-   ##
==========================================
- Coverage   66.74%   63.53%   -3.22%     
==========================================
  Files         942      466     -476     
  Lines       45834    28682   -17152     
  Branches     4400        0    -4400     
==========================================
- Hits        30592    18222   -12370     
+ Misses      15114    10460    -4654     
+ Partials      128        0     -128     

Flag	Coverage Δ
cypress	?
javascript	?
python	63.53% <ø> (-0.67%)	⬇️

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

Impacted Files	Coverage Δ
superset/db_engines/hive.py	0.00% <0.00%> (-85.72%)	⬇️
superset/sql_validators/postgres.py	50.00% <0.00%> (-50.00%)	⬇️
superset/db_engine_specs/hive.py	54.61% <0.00%> (-29.62%)	⬇️
superset/db_engine_specs/presto.py	69.95% <0.00%> (-12.45%)	⬇️
superset/db_engine_specs/sqlite.py	65.62% <0.00%> (-9.38%)	⬇️
superset/utils/celery.py	96.42% <0.00%> (-3.58%)	⬇️
superset/examples/world_bank.py	97.10% <0.00%> (-2.90%)	⬇️
superset/db_engine_specs/postgres.py	97.56% <0.00%> (-2.44%)	⬇️
superset/examples/birth_names.py	96.51% <0.00%> (-2.33%)	⬇️
superset/views/database/mixins.py	80.70% <0.00%> (-1.76%)	⬇️
... and 487 more

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[kgabryje]

closes #11968

[adam-stasiak]

Tested - no refetch data when doing different operation than filtering (left side of explore view). OK!

[rusackas]

LGTM!

[kgabryje]

@rusackas @junlincc Do you think we can merge it?