Remove the rest of the code that assumes that either group0 does not exist yet or a cluster is till not upgraded to raft topology. Both of those are not supported any more.
No need to backport since we remove functionality here.
Closesscylladb/scylladb#28841
* github.com:scylladb/scylladb:
service level: remove version 1 service level code
features: move GROUP0_SCHEMA_VERSIONING to deprecated features list
migration_manager: remove unused forward definitions
test: remove unused code
auth: drop auth_migration_listener since it does nothing now
schema: drop schema_registry_entry::maybe_sync() function
schema: drop make_table_deleting_mutations since it should not be needed with raft
schema: remove calculate_schema_digest function
schema: drop recalculate_schema_version function and its uses
migration_manager: drop check for group0_schema_versioning feature
cdc: drop usage of cdc_local table and v1 generation definition
storage_service: no need to add yourself to the topology during reboot since raft state loading already did it
storage_service: remove unused functions
group0: drop with_raft() function from group0_guard since it always returns true now
gossiper: do not gossip TOKENS and CDC_GENERATION_ID any more
gossiper: drop tokens from loaded_endpoint_state
gossiper: remove unused functions
storage_service: do not pass loaded_peer_features to join_topology()
storage_service: remove unused fields from replacement_info
gossiper: drop is_safe_for_restart() function and its use
storage_service: remove unused variables from join_topology
gossiper: remove the code that was only used in gossiper topology
storage_service: drop the check for raft mode from recovery code
cdc: remove legacy code
test: remove unused injection points
auth: remove legacy auth mode and upgrade code
treewide: remove schema pull code since we never pull schema any more
raft topology: drop upgrade_state and its type from the topology state machine since it is not used any longer
group0: hoist the checks for an illegal upgrade into main.cc
api: drop get_topology_upgrade_state and always report upgrade status as done
service_level_controller: drop service level upgrade code
test: drop run_with_raft_recovery parameter to cql_test_env
group0: get rid of group0_upgrade_state
storage_service: drop topology_change_kind as it is no longer needed
storage_service: drop check_ability_to_perform_topology_operation since no upgrades can happen any more
service_storage: remove unused functions
storage_service: remove non raft rebuild code
storage_service: set topology change kind only once
group0: drop in_recovery function and its uses
group0: rename use_raft to maintenance_mode and make it sync
475220b9c9