BUG/MEDIUM: checks: unchecked servers could not be enabled anymore

Recent fix 02541e8 (BUG/MEDIUM: checks: servers must not start in
slowstart mode) failed to consider one case : a server chich is not
checked at all can be disabled and has to support being enabled
again. So we must also enter the set_server_up() function when the
checks are totally disabled.

No backport is needed.
1 file changed