Revert temporary cloud test and docker dependency overrides

Restore engine-tests-cloud to only run on main branch pushes and
re-add the engine-tests-docker dependency. These were temporarily
removed for faster iteration during the CI migration.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: eakmanrq <6326532+eakmanrq@users.noreply.github.com>

Author: eakmanrq

.github/workflows/pr.yaml

@@ -285,9 +285,8 @@ jobs:
           retention-days: 7
 
   engine-tests-cloud:
-    # TODO: revert back to: needs: engine-tests-docker
-    # TODO: revert back to: if: github.ref == 'refs/heads/main'
-    if: true
+    needs: engine-tests-docker
+    if: github.ref == 'refs/heads/main'
     runs-on: ubuntu-latest
     timeout-minutes: 25
     strategy: