Revert "CI: Allow github merge queue to run build tests (#2334)"

This reverts commit f2f21b5.

Author: yadij

.github/workflows/slow.yaml

@@ -17,9 +17,6 @@ on:
   # allows to run this workflow manually from the Actions tab
   workflow_dispatch:
 
-  merge_group:
-    branches: [ "v7" ]
-
 concurrency:
   # Cancel ongoing tests in case of push to staging branch.
   group: ${{ github.workflow }}-${{ github.ref }}