When a node is in the `left_token_ring` state, we don't know how
it has ended up in this state. We cannot distinguish a node that
has finished decommissioning from a node that has failed bootstrap.
The main problem it causes is that we incorrectly send the
`barrier_and_drain` command to a node that has failed
bootstrapping or replacing. We must do it for a node that has
finished decommissioning because it could still coordinate
requests. However, since we cannot distinguish nodes in the
`left_token_ring` state, we must send the command to all of them.
This issue appeared in scylladb/scylladb#16797 and this PR is
a follow-up that fixes it.
The solution is changing `left_token_ring` from a node state
to a transition state.
Fixesscylladb/scylladb#16944Closesscylladb/scylladb#17009
* github.com:scylladb/scylladb:
docs: dev: topology-over-raft: document the left_token_ring state
topology_coordinator: adjust reason string in left_token_ring handler
raft topology: make left_token_ring a transition state
topology_coordinator: rollback_current_topology_op: remove unused exclude_nodes
0912d2a2c6