This patch introduces raft-based service levels.
The difference to the current method of working is:
- service levels are stored in `system.service_levels_v2`
- reads are executed with `LOCAL_ONE`
- writes are done via raft group0 operation
Service levels are migrated to v2 in topology upgrade.
After the service levels are migrated, `key: service_level_v2_status; value: data_migrated` is written to `system.scylla_local` table. If this row is present, raft data accessor is created from the beginning and it handles recovery mode procedure (service levels will be read from v2 table even if consistent topology is disabled then)
Fixes#17926Closesscylladb/scylladb#16585
* github.com:scylladb/scylladb:
test: test service levels v2 works in recovery mode
test: add test for service levels migration
test: add test for service levels snapshot
test:topology: extract `trigger_snapshot` to utils
main: create raft dda if sl data was migrated
service:qos: store information about sl data migration
service:qos: service levels migration
main: assign standard service level DDA before starting group0
service:qos: fix `is_v2()` method
service:qos: add a method to upgrade data accessor
test: add unit_test_raft_service_levels_accessor
service:storage_service: add support for service levels raft snapshot
service:qos: add abort_source for group0 operations
service:qos: raft service level distributed data accessor
service:qos: use group0_guard in data accessor
cql3:statements: run service level statements on shard0 with raft guard
test: fix overrides in unit_test_service_levels_accessor
service:qos: fix indentation
service:qos: coroutinize some of the methods
db:system_keyspace: add `SERVICE_LEVELS_V2` table
service:qos: extract common service levels' table functions
f23f8f81bf