Issues and merge requests imported from GitHub are having state_id
set to null. This fixes the GitHub project importer and schedule
migrations to fix state_id.
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/20724 removed
`Gitlab::Git::RepositoryMirroring::RemoteError`, but this was still
being handled in the Bitbucket Server importer and only encountered if
some exception other than `Gitlab::Shell::Error` were thrown.