Shutdown the Snapshot Service early (#8658)

* Shutdown the Snapshot Service when shutting down the runner

* Rename `service` to `client_service`

* Fix tests

rpc/src/v1/tests/helpers/snapshot_service.rs

@@ -50,4 +50,5 @@ impl SnapshotService for TestSnapshotService {
 	fn abort_restore(&self) { }
 	fn restore_state_chunk(&self, _hash: H256, _chunk: Bytes) { }
 	fn restore_block_chunk(&self, _hash: H256, _chunk: Bytes) { }
+	fn shutdown(&self) { }
 }