Bugfix:
with the scenario if we force assigned a slot to other master,
old master will lose the slot ownership, then old master will
call the function delKeysInSlot() to delete all keys which in
the slot. These delete operations should replicate to replicas,
avoid the data divergence issue in master and replicas.
Additionally, in this case, we now call:
* signalModifiedKey (to invalidate WATCH)
* moduleNotifyKeyspaceEvent (key space notification for modules)
* dirty++ (to signal that the persistence file may be outdated)
Co-authored-by: weimeng <weimeng@didiglobal.com>
Co-authored-by: Madelyn Olson <madelyneolson@gmail.com>
