Merge branch 'jarv/check-all-secondaries' into 'master'

Will check replication status on all secondaries as well.

Closes #764

See merge request gitlab-com/migration!200
2 jobs for master in 21 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #2733450
references

00:00:12

passed #2733449
shellcheck

00:00:21