Some assorted cleanups here: consolidation of schema agreement waiting
into a single place and removing unused code from the gossiper.
CI: https://jenkins.scylladb.com/job/scylla-master/job/scylla-ci/1458/
Reviewed-by: Konstantin Osipov <kostja@scylladb.com>
* gleb/gossiper-cleanups of github.com:scylladb/scylla-dev:
storage_service: avoid unneeded copies in on_change
storage_service: remove check that is always true
storage_service: rename handle_state_removing to handle_state_removed
storage_service: avoid string copy
storage_service: delete code that handled REMOVING_TOKENS state
gossiper: remove code related to advertising REMOVING_TOKEN state
migration_manager: add wait_for_schema_agreement() function
5861d15912