build: remove github actions dependabot on release branches (#44054)

.github/dependabot.yml

@@ -11,38 +11,6 @@ updates:
       - "no-backport"
       - "semver/none"
     target-branch: main
-  - package-ecosystem: github-actions
-    directory: /
-    schedule:
-      interval: weekly
-    labels:
-      - "backport-check-skip"
-      - "semver/none"
-    target-branch: 33-x-y
-  - package-ecosystem: github-actions
-    directory: /
-    schedule:
-      interval: weekly
-    labels:
-      - "backport-check-skip"
-      - "semver/none"
-    target-branch: 32-x-y
-  - package-ecosystem: github-actions
-    directory: /
-    schedule:
-      interval: weekly
-    labels:
-      - "backport-check-skip"
-      - "semver/none"
-    target-branch: 31-x-y
-  - package-ecosystem: github-actions
-    directory: /
-    schedule:
-      interval: weekly
-    labels:
-      - "backport-check-skip"
-      - "semver/none"
-    target-branch: 30-x-y
   - package-ecosystem: npm
     directories:
       - /