`storage_service::get_tablets_migration_status()` returns the
keyspace-level migration status, indicating whether migration has not
started, is in progress, or has completed, and for migrating keyspaces
also returns per-node migration statuses. Rename it to
`get_tablets_migration_status_with_node_details()` and introduce a new
`get_tablets_migration_status()` that returns only the keyspace-level
status.
This prepares the function for reuse in the next patches, which will add
a virtual task for vnodes-to-tablets migrations. Several task-manager
paths will only need the keyspace-level migration state, not per-node
information.
Signed-off-by: Nikos Dragazis <nikolaos.dragazis@scylladb.com>
46e3902daa