ci: post regression notifications if scheduled tests do not succeed

[zimeg]

Summary

This PR follows #1374 and #1375 to send regression notifications if scheduled tests do not succeed instead of just during failures. Fixes an issue where test timeout did not post a message.

Testing

📺 Planning to add a few commits that confirm !success is the correct operation for both "cancelled" and "failure" states. Since these steps run when scheduled on "main" outside of this PR, these are both events we want to capture I believe.

Category

• Others

Requirements

Please read the Contributing guidelines and Code of Conduct before creating this issue or pull request. By submitting, you are agreeing to those rules.

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.
• I've run ./scripts/install_all_and_run_tests.sh after making the changes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.00%. Comparing base (e21c4e8) to head (433e2dd).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1376   +/-   ##
=======================================
  Coverage   91.00%   91.00%           
=======================================
  Files         222      222           
  Lines        7512     7512           
=======================================
  Hits         6836     6836           
  Misses        676      676           

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[zimeg]

📚 Reference: https://docs.github.com/en/actions/reference/workflows-and-actions/expressions#status-check-functions

[mwbrooks]

Great idea!