chore(ci): serialize E2E test runs across PRs (#678)

Author: bhabalan

.github/workflows/pull-request.yml

@@ -182,6 +182,9 @@ jobs:
     continue-on-error: true
     needs: [install, build]
     if: contains(toJson(github.event.pull_request.labels), 'run_e2e')
+    concurrency:
+      group: e2e-meetings
+      cancel-in-progress: false
 
     steps:
       - name: Checkout Project
@@ -216,6 +219,9 @@ jobs:
     runs-on: ubuntu-latest
     needs: [install, build]
     if: contains(toJson(github.event.pull_request.labels), 'run_e2e')
+    concurrency:
+      group: e2e-cc-widgets
+      cancel-in-progress: false
 
     steps:
       - name: Checkout Project