Cassandra changed their system tables in 3.0. We migrated to the new system table layout in 2017, in ScyllaDB 2.0.
System tables introduced in Cassandra 3.0, as well as the 3.0 variant of pre-existing system tables were added to the db::system_table::v3 namespace.
We ended up adding some new ScyllaDB-only system tables to this namespace as well.
As the dust settled, most of the v3 system tables ended up being either simple aliases to non-v3 tables, or new tables.
Either way, the codebase uses just one variant of each table for a long time now the v3:: distinction is pointless.
Remove the v3 namespace and unify the table listing under the top-level db::system_keyspace scope.
Code cleanup, no backport
Closesscylladb/scylladb#28146
* github.com:scylladb/scylladb:
db/system_keyspace: move remining tables out of v3 keyspace
db/system_keyspace: relocate truncated() and commitlog_cleanups()
db/system_keyspace: drop v3::local()
db/system_keyspace: remove duplicate table names from v3
36347c3ce9