Fixes a problem when raft-based topology is enabled, which loads
topology from storage. It starts by clearing topology and then adding
nodes one by one. Before this patch, this violates internal invariant
of topology object which puts the local node as the first node. This
would manifest by triggering an assert in topology::pop_node() which
throws if popping the node at index 0 in order to keep the information
about local node around. This is normally prevented by a check in
topology::remove_node() which avoid calling pop_node() if removing the
local node. But since there is no node which is marked as local, this
check allows the first node to be popped.
To fix the problem I lift the invariant that local node is always in
_nodes. We still have information about local node in config. Instead
of keeping it in _nodes, we recognize it as part of indexing. We also
allow removing the local node like a regular node.
The path which reloads topology works correctly after this, the local
node will be recognized when (if) it is added to the topology.
Fixes#13495Closes#13498
* github.com:scylladb/scylladb:
locator: topology: Fix move assignment
locator: topology: Add printer
tests: topology: Test that topology clearing preserves information about local node
locator: topology: Recognize local node as part of indexing it
locator: topology: Fix get_location(ep) for local node
locator: topology: Fix typo
locator: topology: Preserve config when cloning
f7408130c9