devops: migrate to GitHub App for automation (#3131)

Author: mxschmitt

.github/workflows/trigger_internal_tests.yml

@@ -11,11 +11,17 @@ jobs:
     name: "trigger"
     runs-on: ubuntu-24.04
     steps:
+    - uses: actions/create-github-app-token@v1
+      id: app-token
+      with:
+        app-id: ${{ vars.PLAYWRIGHT_APP_ID }}
+        private-key: ${{ secrets.PLAYWRIGHT_PRIVATE_KEY }}
+        repositories: playwright-browsers
     - run: |
-        curl -X POST \
+        curl -X POST --fail \
           -H "Accept: application/vnd.github.v3+json" \
           -H "Authorization: token ${GH_TOKEN}" \
           --data "{\"event_type\": \"playwright_tests_dotnet\", \"client_payload\": {\"ref\": \"${GITHUB_SHA}\"}}" \
           https://api.github.com/repos/microsoft/playwright-browsers/dispatches
       env:
-        GH_TOKEN: ${{ secrets.REPOSITORY_DISPATCH_PERSONAL_ACCESS_TOKEN }}
+        GH_TOKEN: ${{ steps.app-token.outputs.token }}