It can happen that a node is lost during tablet migration involving that node. Migration will be stuck, blocking topology state machine. To recover from this, the current procedure is for the admin to execute nodetool removenode or replacing the node. This marks the node as "ignored" and tablet state machine can pick this up and abort the migration.
This PR implements the handling for streaming stage only and adds a test for it. Checking other stages needs more work with failure injection to inject failures into specific barrier.
To handle streaming failure two new stages are introduced -- cleanup_target and revert_migration. The former is to clean the pending replica that could receive some data by the time streaming stopped working, the latter is like end_migration, but doesn't commit the new_replicas into replicas field.
refs: #16527Closesscylladb/scylladb#17360
* github.com:scylladb/scylladb:
test/topology: Add checking error paths for failed migration
topology.tablets_migration: Handle failed streaming
topology.tablets_migration: Add cleanup_target transition stage
topology.tablets_migration: Add revert_migration transition stage
storage_service: Rewrap cleanup stage checking in cleanup_tablet()
test/topology: Move helpers to get tablet replicas to pylib
e63d8ae272