feat: hide datasource legacy based on featureflag

[hughhhh]

SUMMARY

Hiding legacy datasource view based upon react_crud_views flag

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

Flag: False

Flag: True

TEST PLAN

1. Goto superset/config.py file
2. Change ENABLE_REACT_CRUD_VIEWS to false
3. Check if use Use Legacy Datasource Editor btn is hidden in DatasourceModal view

ADDITIONAL INFORMATION

• Has associated issue:
• Changes UI
• Requires DB Migration.
• Confirm DB Migration upgrade and downgrade tested.
• Introduces new feature or API
• Removes existing feature or API

[github-actions]

Please format your PR title to match: ^(build|chore|ci|docs|feat|fix|perf|refactor|style|test|other)((.+))?:\s.+!

All good!

[codecov-io]

Codecov Report

Merging #11371 into master will increase coverage by 0.39%.
The diff coverage is 75.00%.

@@            Coverage Diff             @@
##           master   #11371      +/-   ##
==========================================
+ Coverage   66.12%   66.52%   +0.39%     
==========================================
  Files         841      859      +18     
  Lines       40156    40965     +809     
  Branches     3685     3687       +2     
==========================================
+ Hits        26554    27252     +698     
- Misses      13501    13612     +111     
  Partials      101      101              

Flag	Coverage Δ
#cypress	56.30% <50.00%> (-0.02%)	⬇️
#javascript	62.95% <57.14%> (-0.01%)	⬇️
#python	62.02% <100.00%> (+0.78%)	⬆️

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

Impacted Files	Coverage Δ
...perset-frontend/src/datasource/DatasourceModal.tsx	92.72% <66.66%> (-3.28%)	⬇️
superset-frontend/src/featureFlags.ts	100.00% <100.00%> (ø)
superset/config.py	90.18% <100.00%> (ø)
superset/models/annotations.py	89.65% <0.00%> (-2.94%)	⬇️
...set-frontend/src/dashboard/util/getDropPosition.js	92.06% <0.00%> (-1.59%)	⬇️
...t/annotation_layers/annotations/commands/delete.py	85.18% <0.00%> (ø)
superset/annotation_layers/commands/bulk_delete.py	85.71% <0.00%> (ø)
superset/annotation_layers/filters.py	92.85% <0.00%> (ø)
superset/annotation_layers/annotations/filters.py	92.85% <0.00%> (ø)
superset/annotation_layers/annotations/schemas.py	87.09% <0.00%> (ø)
... and 14 more

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[willbarrett]

@lilykuang would you mind giving this a look?

[nytai]

LGTM, but I'm curious what's the motivation for this? Is the idea to fully deprecate the old datasource editor. We have been getting quite a few bug reports on the new datasource editor, are we certain the new datasource editor is at 100% feature parity?

[willbarrett]

LGTM once green

[nytai]

retriggering CI, since #11433 merged