Merge branch '501105-follow-up-use-lb' into 'master'

fix: Update DB healthcheck to use conn.load_balancer for deriving DB

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/175752



Merged-by: Krasimir Angelov <kangelov@gitlab.com>
Approved-by: Leonardo da Rosa <ldarosa@gitlab.com>
Approved-by: Krasimir Angelov <kangelov@gitlab.com>
Approved-by: Luke Duncalfe <lduncalfe@gitlab.com>
Reviewed-by: Leonardo da Rosa <ldarosa@gitlab.com>
Co-authored-by: Lucas Charles <lcharles@gitlab.com>