In https://gitlab.com/gitlab-org/gitlab/-/merge_requests/29420,
we started filtering the branches that we update on push. It only
looks at branches with open MRs.

It caused a regression wherein closed MRs approvals weren't being
reset even when `reset_approvals_on_push` setting is set to `true`.

This updates the `MergeRequests::PushedBranchesService` to include
closed MRs with matching source branches as well.