fix: Update migration logic in #27119

[john-bodley]

SUMMARY

This PR is a follow up #28422 (which needs to be cherry-picked to remedy an issue, but can't include a migration). Specifically it also adds a new migration to resize specific columns back to LONGTEXT if the previous migration has already been run. If not, the migration is a no-op.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

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

All modified and coverable lines are covered by tests ✅

Project coverage is 83.48%. Comparing base (76d897e) to head (19423bc).
Report is 150 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #28482       +/-   ##
===========================================
+ Coverage   60.48%   83.48%   +22.99%     
===========================================
  Files        1931      521     -1410     
  Lines       76236    37484    -38752     
  Branches     8568        0     -8568     
===========================================
- Hits        46114    31294    -14820     
+ Misses      28017     6190    -21827     
+ Partials     2105        0     -2105     

Flag	Coverage Δ
hive	49.09% <ø> (-0.07%)	⬇️
javascript	?
mysql	77.15% <ø> (?)
postgres	77.28% <ø> (?)
presto	53.64% <ø> (-0.16%)	⬇️
python	83.48% <ø> (+19.99%)	⬆️
sqlite	76.73% <ø> (?)
unit	58.94% <ø> (+1.31%)	⬆️

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

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[mistercrunch]

LGTM