Ensure all alerts correctly work when Mimir is deployed using the read-write deployment mode

[pracucci]

We should check all Mimir alerts 1-by-1, to ensure all of them correctly work (e.g. metrics are correctly queried) when Mimir is deployed in read-write deployment mode.

For example, any alert querying metrics with the container label matcher may not work (because container names are different). We could also consider a linter failing CI if anyone is using container label matcher in alerts.

[pracucci]

Also, the MimirGossipMembersMismatch alert doesn't work with read-write deployment mode because mimir-write.*|mimir-read.*|mimir-backend.* is missing from the configured ring_members.

Edit: fixed in #3489.