chore: Remove obsolete Druid NoSQL REGEX operator

[john-bodley]

SUMMARY

Whilst reading over this code I realized that the REGEX filter operator is unused—a byproduct of the Druid NoSQL connector which has been removed.

This PR removes the obsolete options from the UI controls to prevent erroneous backend errors.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

BEFORE

AFTER

TESTING INSTRUCTIONS

CI.

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 #24415 (a010793) into master (b68de27) will decrease coverage by 0.01%.
The diff coverage is n/a.

❗ Current head a010793 differs from pull request most recent head 499a197. Consider uploading reports for the commit 499a197 to get more accurate results

@@            Coverage Diff             @@
##           master   #24415      +/-   ##
==========================================
- Coverage   68.93%   68.93%   -0.01%     
==========================================
  Files        1904     1904              
  Lines       73879    73877       -2     
  Branches     8119     8119              
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- Hits        50928    50926       -2     
  Misses      20840    20840              
  Partials     2111     2111              

Flag	Coverage Δ
hive	53.94% <ø> (-0.01%)	⬇️
javascript	55.65% <ø> (ø)
mysql	79.25% <ø> (-0.01%)	⬇️
postgres	79.34% <ø> (-0.01%)	⬇️
presto	53.86% <ø> (-0.01%)	⬇️
python	83.33% <ø> (-0.01%)	⬇️
sqlite	77.83% <ø> (-0.01%)	⬇️
unit	54.64% <ø> (-0.01%)	⬇️

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Impacted Files	Coverage Δ
superset-frontend/src/explore/constants.ts	100.00% <ø> (ø)
superset/utils/core.py	91.53% <ø> (-0.02%)	⬇️

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[michael-s-molina]

LGTM