R1:3fda965288cc

When multiple web hosts are in service, don't require setup warnings to be dismissed on each one

Summary:
Fixes T10876. Currently, we can end up with a setup warning banner sticking on each web device, since the state is stored in local cache.

Instead:

- When we actually run the setup checks, save the current state in the database.
- Before we show a cached banner, make sure the database still says the checks are a problem.

This could lead to some inconsistencies if setup checks legitimately pass…