R1:78040e0ff577

Run "DatabaseSetup" checks against all configured hosts

Summary:
Ref T10759. Currently, these checks run only against configured masters. Instead, check every host.

These checks also sort of cheat through restart during a recovery, when some hosts will be unreachable: they test for "disaster" by seeing if no masters are reachable, and just skip all the checks in that case.

This is bad for at least two reasons:

- After recent changes, it is possible that //some// masters are dead but it's still OK to…