ci: drop cross-workflow heavy pool lock that cancelled Web E2E

Queued Playwright jobs were cancelled on self-hosted while waiting on
evoo-self-hosted-heavy. Keep validate matrix max-parallel: 1 for buildkit.

Co-authored-by: cynarAI <cynarAI@users.noreply.github.com>

.github/workflows/playwright.yml

@@ -56,7 +56,7 @@ jobs:
     runs-on: [self-hosted, evoo-ci, Linux]
     timeout-minutes: 45
     concurrency:
-      group: ${{ inputs.publish_report && 'playwright-publication' || 'evoo-self-hosted-heavy' }}
+      group: ${{ inputs.publish_report && 'playwright-publication' || format('playwright-{0}', github.run_id) }}
       cancel-in-progress: false
     steps:
       - uses: actions/checkout@v5

.github/workflows/publish-server-image.yml

@@ -53,10 +53,6 @@ jobs:
     if: github.event_name == 'pull_request'
     runs-on: [self-hosted, evoo-ci, Linux]
     timeout-minutes: 90
-    # Same pool as Web E2E; image builds starve the dev servers Playwright needs.
-    concurrency:
-      group: evoo-self-hosted-heavy
-      cancel-in-progress: false
     permissions:
       contents: read
     strategy: