[Chapel Merge] Serialize full check runs per event type

Branch: refs/heads/main
Revision: 146ab84a4ec5b9cdc4ed33298060ba34c415176a
Author: arifthpe
Link: Serialize full check runs per event type by arifthpe · Pull Request #29278 · chapel-lang/chapel · GitHub
Log Message:
Serialize full check runs per event type (#29278)

Add a concurrency setting to trigger-full-checks causing it to run
serially per triggering event type.

This means that a manual-, schedule-, and push-triggered run could all
run concurrently, but additional invocations from the same trigger would
have to wait. The intention is to avoid tying up a lot of resources from
back-to-back PR merges (push events), which may come in bursts but do
not require timely feedback on post-merge testing.

[reviewed by @jabraham17 , thanks!]

Compare: Comparing 16be1e3f7960bd29d2ef58e6188c87f65ab9c933...d04f6dc27d167a43d30d4b0a3ffc953cb8b936a2 · chapel-lang/chapel · GitHub

Diff:
M .github/workflows/trigger-full-checks.yml
https://github.com/chapel-lang/chapel/pull/29278.diff