[Bug] Unused resources can be left over on operator upgrade

> I noticed one other funny effect from the https://github.com/cryostatio/cryostat-operator/pull/897 upgrade steps - the old separate Grafana Route gets left behind. That makes sense since it was an upgrade from 2.4.0 to 4.0.0-dev, and in 2.x we exposed Grafana as a separate Route. In 3.0 it's exposed as a path on the auth proxy with the same Route. I think the old leftover Route is harmless, but also useless.

Oh right, how about we delete the old Grafana route in the reconciler, similar to how we do it for CORS modifications?

https://github.com/cryostatio/cryostat-operator/blob/0ec9a84ffded9865671402790379c2884097f456/internal/controllers/openshift.go#L41-L42

_Originally posted by @tthvo in https://github.com/cryostatio/cryostat-operator/issues/968#issuecomment-2494328149_