the merge queue needs help from our status checks to actually work

https://docs.github.com/en/repositories/configuring-branches-and-merges-in-your-repository/configuring-pull-request-merges/managing-a-merge-queue#triggering-merge-group-checks-with-github-actions says something about `on: merge_group:` and we don't have that config, so the merge queue is forever stuck. I'm turning it off for now until we know what config we need.