CI - Fix the merge queue (#3571)

# Description of Changes

The merge queue was (partly) getting borked because we were putting all
non-PR CI events into the same concurrency group, which meant they all
non-PR CI jobs would run sequentially instead of running in parallel.
This sometimes caused _painfully_ long delays in the merge queue.

This was due to my misunderstanding in
#3501 (comment),
where I didn't realize that `cancel-in-progress: false` would cause
everything to queue up.

Now, for non-PR events, we append the commit SHA to the concurrency
group. For merge queue events, this should be the SHA of the ephemeral
merge commit that GH creates, so it will never conflict. For push events
or manual workflow dispatch events, the SHA should be a sane way to
recognize/cancel redundant events.

# API and ABI breaking changes

None. CI-only change.

# Expected complexity level and risk

1

# Testing

- [x] PR CI passes on this PR
- [x] PR CI is still canceled on this PR if a new commit is pushed

Unfortunately it's hard to test the behavior for non-PR events without
merging and seeing if it works.

---------

Co-authored-by: Zeke Foppa <bfops@users.noreply.github.com>

Author: bfops

.github/workflows/ci.yml

@@ -14,10 +14,8 @@ on:
 name: CI
 
 concurrency:
-  # When a PR number isn't available, the event won't be a `pull_request` event so it won't matter.
-  group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
-  # Only cancel when the event is a pull_request
-  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.event.inputs.pr_number || format('sha-%s', github.sha) }}
+  cancel-in-progress: true
 
 jobs:
   docker_smoketests:

.github/workflows/csharp-test.yml

@@ -7,10 +7,8 @@ on:
   pull_request:
 
 concurrency:
-  # When a PR number isn't available, the event won't be a `pull_request` event so it won't matter.
-  group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
-  # Only cancel when the event is a pull_request
-  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || format('sha-%s', github.sha) }}
+  cancel-in-progress: true
 
 jobs:
   unity-testsuite:

.github/workflows/internal-tests.yml

@@ -10,10 +10,8 @@ permissions:
   contents: read
 
 concurrency:
-  # When a PR number isn't available, the event won't be a `pull_request` event so it won't matter.
-  group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
-  # Only cancel when the event is a pull_request
-  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || format('sha-%s', github.sha) }}
+  cancel-in-progress: true
 
 jobs:
   run-tests:

.github/workflows/typescript-test.yml

@@ -8,10 +8,8 @@ on:
   merge_group:
 
 concurrency:
-  # When a PR number isn't available, the event won't be a `pull_request` event so it won't matter.
-  group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
-  # Only cancel when the event is a pull_request
-  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || format('sha-%s', github.sha) }}
+  cancel-in-progress: true
 
 jobs:
   build-and-test: