Add integration tests for TABLETS_ROUTING_V2

Cover the end-to-end behaviour against a live ScyllaDB started with the
`STRONGLY_CONSISTENT_TABLES` cluster feature: v2 negotiation,
payload-driven cache population, the tablet_version_block matching rules
(no payload on a matching block, exactly one matching value per index,
precedence over v1), the protocol error on a missing block, and
leader-aware routing targeting the Raft leader for a strongly-consistent
keyspace.

Author: dawmd