ci/check-cherry-picks: move from maintainers/scripts

The script is part of CI and changes to it should be reviewed by the CI
owners. Thus moving it to ci/ is the most sensible thing to do.

(cherry picked from commit ad4b36d2d2)

.github/workflows/check-cherry-picks.yml

@@ -28,4 +28,4 @@ jobs:
           BASE_SHA: ${{ github.event.pull_request.base.sha }}
           HEAD_SHA: ${{ github.event.pull_request.head.sha }}
         run: |
-          ./trusted/maintainers/scripts/check-cherry-picks.sh "$BASE_SHA" "$HEAD_SHA"
+          ./trusted/ci/check-cherry-picks.sh "$BASE_SHA" "$HEAD_SHA"