Retrieval of tablet stats must be serialized with mutation to token metadata, as the former requires tablet id stability.
If tablet split is finalized while retrieving stats, the saved erm, used by all shards, can have a lower tablet count than the one in a particular shard, causing an abort as tablet map requires that any id feeded into it is lower than its current tablet count.
Fixes#18085.
Closesscylladb/scylladb#18287
* github.com:scylladb/scylladb:
test: Fix flakiness in topology_experimental_raft/test_tablets
service: Use tablet read selector to determine which replica to account table stats
storage_service: Fix race between tablet split and stats retrieval
2d79b0106c