storage_service: get_changed_ranges_for_leaving: release token_metadata_ptr sooner
storage_service: get_changed_ranges_for_leaving: release token_metadata_ptr sooner

No need to hold on to the shared token_metadata_ptr
after we got clone_after_all_left().

Signed-off-by: Benny Halevy <23c997c90eb8537635e9392d48e7af1bf1b2ca22@scylladb.com>

scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla