This removes the Query method from CodeMonitorStore by replacing the
last reference to it with the pre-existing store method MonitorByIDInt64
All the ownerByID is doing is fetching the of a monitor from the store,
then checking the permissions, but it rolls its own SQL rather than leaving
that to the store. Instead, this just fetches the whole monitor and returns
the owner ID. Most places this is called, we can make this more efficient
by just checking the ID of an already-fetched monitor, but that's a larger
refactor than I want to tackle in this PR.
