Limit CI push triggers to main and stable-* branches (#30934)

.github/workflows/lint-ruby.yml

@@ -1,9 +1,10 @@
 name: Ruby Linting
 on:
+  merge_group:
   push:
-    branches-ignore:
-      - 'dependabot/**'
-      - 'renovate/**'
+    branches:
+      - 'main'
+      - 'stable-*'
     paths:
       - 'Gemfile*'
       - '.rubocop*.yml'