chore: remove deprecated api /superset/available_domains

[dpgaspar]

SUMMARY

Removes deprecated API /superset/available_domains/

Effort on removing deprecated API from /superset: #24332

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TESTING INSTRUCTIONS

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 #24381 (5c33142) into master (93ba59d) will increase coverage by 0.57%.
The diff coverage is n/a.

❗ Current head 5c33142 differs from pull request most recent head 184469c. Consider uploading reports for the commit 184469c to get more accurate results

@@            Coverage Diff             @@
##           master   #24381      +/-   ##
==========================================
+ Coverage   68.36%   68.94%   +0.57%     
==========================================
  Files        1903     1903              
  Lines       74385    74378       -7     
  Branches     8110     8110              
==========================================
+ Hits        50856    51279     +423     
+ Misses      21417    20987     -430     
  Partials     2112     2112              

Flag	Coverage Δ
hive	?
mysql	79.38% <ø> (?)
postgres	79.44% <ø> (?)
presto	53.81% <ø> (-0.01%)	⬇️
python	83.16% <ø> (+1.19%)	⬆️
sqlite	?
unit	54.30% <ø> (-0.01%)	⬇️

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

Impacted Files	Coverage Δ
superset/views/core.py	76.64% <ø> (+0.23%)	⬆️

... and 42 files with indirect coverage changes

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