fix(ci): run frontend actions based on master, not the fork.

[rusackas]

SUMMARY

This should make it so forks can leverage our secrets (e.g. codecov key) and not need to rebase.

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

[rusackas]

@mistercrunch fixed!

(cc @michael-s-molina since we discussed this earlier)