Previously semaphore mismatch was checked only in multi-partition
queries and if happened, an internal error was thrown.
This commit pushed the check down to `querier_cache`, so each
`lookup_*_querier` method will check for the mismatch.
What's more, if semaphore mismatch occurs, check whether both semaphores belong
to user. If so, log a warning and drop cached reader instead of
throwing an error.
The mismatch can happen if user's scheduling group changed during
a query. We don't want to throw an error then, but drop and reset
cached reader.
a5fc53aa11