In Scylla, we can have either `closed` or `merged` PRs. Based on that we decide when to start the backport process when the label was added after the PR is closed (or merged),
In https://github.com/scylladb/scylladb/pull/21876 even when adding the proper backport label didn't trigger the backport automation. Https://github.com/scylladb/scylladb/pull/21809/ caused this, we should have left the `state=closed` (this includes both closed and merged PR)
Fixing it
Closes scylladb/scylladb#21906
(cherry picked from commit b4b7617554)
Closes scylladb/scylladb#21922