This reverts commits bf333eaea2 and
6f69a445bd.
The commit linter needs to run on event `pull_request_target` to have
access to its secret token, which means we cannot have a dependency on
that job from another workflow that is run as a result of the
`pull_request` event.
Additionally, the linters were no longer run for first-time
contributors. This isn't a huge problem but it was nice that a
preliminary check took place before running the full CI on their PRs.