The release/publish behavior upon merging of a changeset PR into its base branch relies on it deleting all changeset files in the .changeset folder. If a changeset file is erroneously not deleted, the release/publish won't happen; take #2065 as an example.

We should make sure that the changeset PR deletes all changesets. If it doesn't, it shouldn't be mergable into its base branch. Besides workflow changes, this might require additional repository rules for changeset-release/* branches.