The code in `global_token_metadata_barrier` allows drain to fail.
Then, it relies on fencing. However, we don't send the barrier
command to a decommissioning node, which may still receive requests.
The node may accept a write with a stale topology version. It makes
fencing ineffective.
Fix this issue by sending the barrier command to a decommissioning
node.
The raft-based topology is moved out of experimental in 6.0, no need
to backport the patch.
Fixesscylladb/scylladb#17108Closesscylladb/scylladb#18599
a04ea7b997