fix(ci): use PR number in MicroShift workflow concurrency group (kroxylicious#3583)

* fix(ci): use PR number in MicroShift workflow concurrency group

When triggered via workflow_run, github.ref resolves to refs/heads/main
for all PRs, causing every PR build to share the same concurrency group
and cancel each other.

Use github.event.workflow_run.pull_requests[0].number (the originating
PR number) so each PR gets its own group, consistent with other workflows
that use github.event.pull_request.number || github.ref.

Assisted-by: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: Sam Barker <sam@quadrocket.co.uk>

* fix(ci): use head_branch for concurrency group and head_sha for checkout

For workflow_run triggers, github.event.pull_request is unavailable.
Using head_branch for the concurrency group is more reliable than
pull_requests[0].number and works for fork PRs too.

Checking out head_sha ensures we test the PR's actual code rather than
always defaulting to the main branch — the previous bug meant every
workflow_run trigger ran the main branch, not the PR under test.

Assisted-by: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: Sam Barker <sam@quadrocket.co.uk>

---------

Signed-off-by: Sam Barker <sam@quadrocket.co.uk>

Author: SamBarker

.github/workflows/operator-tests-microshift.yaml

@@ -44,7 +44,7 @@ on:
         required: false
 
 concurrency:
-  group: ${{ github.workflow }}-${{ github.ref }}
+  group: ${{ github.workflow }}-${{ github.event.workflow_run.head_branch || github.ref }}
   cancel-in-progress: true
 
 jobs:
@@ -54,9 +54,6 @@ jobs:
     outputs:
       pull-secret-check: ${{ steps.pull-check.outputs.pullsecret }}
     steps:
-        - name: Checkout source
-          uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd
-
         - name: 'Test for presence of Red Hat pull-secret'
           id: pull-check
           env:
@@ -84,6 +81,8 @@ jobs:
 
       - name: Checkout source
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd
+        with:
+          ref: ${{ github.event.workflow_run.head_sha || github.sha }}
 
       - name: Setup Java
         uses: ./.github/actions/common/setup-java