ci: disable CI-taptests-groups auto-trigger (same 403 on jenkins-build-scripts)

All four matrices (tests, tests/unit, tests_with_deps/*) of
CI-taptests-groups fail at the 'Checkout jenkins_build_scripts' step
with:
  fatal: unable to access 'https://github.com/proxysql/jenkins-build-scripts/':
         The requested URL returned error: 403

Same root cause as the CI-repltests / CI-shuntest disabling in the
previous commit: GH_TOKEN_PROXYSQL no longer has access to the
proxysql/jenkins-build-scripts repo. Comment out the workflow_run
trigger so the workflow stops firing automatically on every push;
workflow_dispatch is preserved for manual re-runs once the secret is
refreshed.

.github/workflows/CI-taptests-groups.yml

@@ -2,10 +2,14 @@ name: CI-taptests-groups
 run-name: '${{ github.event.workflow_run && github.event.workflow_run.head_branch || github.ref_name }} ${{ github.workflow }} ${{ github.event.workflow_run && github.event.workflow_run.head_sha || github.sha }}'
 
 on:
+  # Auto-triggering disabled: jenkins-build-scripts repo access currently
+  # returns HTTP 403 from this workflow (same root cause as
+  # CI-repltests / CI-shuntest). Re-enable by restoring the workflow_run
+  # trigger once jenkins-build-scripts access is fixed.
   workflow_dispatch:
-  workflow_run:
-    workflows: [ CI-trigger ]
-    types: [ completed ]
+  # workflow_run:
+  #   workflows: [ CI-trigger ]
+  #   types: [ completed ]
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.event.workflow_run && github.event.workflow_run.head_branch || github.ref_name }}