MNT Run admin and CMS behat tests

We override some default stuff, so lets make sure we're not breaking
anything in lieu of adding our own tests for now.

Author: GuySartorelli

.github/workflows/ci.yml

@@ -9,3 +9,15 @@ jobs:
   ci:
     name: CI
     uses: silverstripe/gha-ci/.github/workflows/ci.yml@v1
+    with:
+      extra_jobs: |
+        - php: 8.0
+          phpunit: false
+          endtoend: true
+          endtoend_suite: admin
+          endtoend_config: vendor/silverstripe/admin/behat.yml
+        - php: 8.1
+          phpunit: false
+          endtoend: true
+          endtoend_suite: cms
+          endtoend_config: vendor/silverstripe/cms/behat.yml