Updating all of the threadFrozenDueToBlock callsites on keyserver is going to be involved. I started working on it, but it required changing a bunch of functionality in keyserver/lib/etc.

I will still consolidate the logic in this stack, specifically to avoid the sketchy CHANGE_ROLE check for server variant of function... but will sequence that after figuring out everything on client.

Depends on D11308

Straightforward refactor, find/replace + flow