Two issues:
1) ShardRegion actor must stop itself when the node is shutting down,
ie. when receiving MemberRemoved(selfAddress)
2) ShardCoordinator must not persist anything when the node is shutting
down. MemberRemoved of other shard regions will trigger Terminated,
which must not be persisted, because then the next coordinator will
replay those events and end up in wrong state. This is a problem
announced itself when using leaving as illustrated in the new test.
To solve the second issue I have added a new ClusterShuttingDown event
that is published before the MemberRemoved events. Note that Terminated
is triggered by MemberRemoved.
(cherry picked from commit 1b272c72597beece9d93f0054f4b58e3d25f9ae2)
