Fixes a shutdown deadlock where a node hangs because `stale_versions_in_use()` blocks on stale `token_metadata` versions held by write handlers whose `MUTATION_DONE` responses can never arrive (transport is already stopped).
Two manifestations depending on whether the shutting-down node is the topology coordinator:
- Coordinator: do_drain → wait_for_group0_stop deadlocks because the topology coordinator fiber is stuck in barrier_and_drain → stale_versions_in_use().
- Non-coordinator: ss::stop → uninit_messaging_service deadlocks because the barrier_and_drain RPC handler holds the gate open.
The non-coordinator case was fixed in PR #24714 (cancel all write requests on storage_proxy shutdown), but its test never actually failed — the write handler always captured the current token_metadata version because `pause_before_barrier_and_drain` used `one_shot=True,` so only the first `barrier_and_drain` was paused. The topology state hadn't advanced by that point, meaning the write handler's ERM version matched the current version and `stale_versions_in_use()` returned immediately. The coordinator case was not covered at all.
Cancel all write response handlers on all shards right after `stop_transport()` in `do_drain()`. This releases their ERMs and the associated stale token_metadata versions, unblocking `stale_versions_in_use()`.
Fixed the test to ensure the write handler holds a stale version: use one_shot=False, let the first barrier_and_drain through (version still current), then wait for the second one (version now stale). Extended to cover both coordinator and non-coordinator shutdown on the same 2-node cluster.
Also includes supporting changes:
- error_injection: release wait_for_message waiters on disable() so the test can atomically unblock paused handlers
- error_injection: add non-shared mode to wait_for_message for per-invocation message semantics
- scylla_cluster.py: allow stop() to bypass start_stop_lock so SIGKILL works while stop_gracefully is blocked
Fixes: SCYLLADB-1842
Refs: scylladb/scylladb#23665
backports: SCYLLADB-1842 reported a failure in 2025.1, so we need to backport to all versions starting from 2025.1
Closesscylladb/scylladb#29882
* https://github.com/scylladb/scylladb:
storage_service: cancel write handlers during drain to prevent shutdown deadlock
test_unfinished_writes_during_shutdown: extend to cover coordinator shutdown
test_unfinished_writes_during_shutdown: fix to reproduce the shutdown deadlock
test_unfinished_writes_during_shutdown: await add_last_node_task instead of cancelling it
test_unfinished_writes_during_shutdown: add timeout and deadlock detection for shutdown_task
test: scylla_cluster: allow stop() to bypass start_stop_lock
error_injection: add non-shared mode to wait_for_message
error_injection: release waiters when injection is disabled
1ed3f5c4af