box: refactor synchro quorum update on deletion from _cluster space

For symmetry with the update of the synchronous replication quorum on
insertion into the `_cluster` space, let's reuse the
`on_replace_cluster_update_quorum` on_commit trigger.

Follows-up tarantool#10087

NO_CHANGELOG=<refactoring>
NO_DOC=<refactoring>
NO_TEST=<refactoring>

Author: CuriousGeorgiy

src/box/alter.cc

@@ -4719,6 +4719,11 @@ on_replace_dd_cluster_delete(const struct replica_def *old_def)
 	if (on_commit == NULL)
 		return -1;
 	txn_stmt_on_commit(stmt, on_commit);
+	on_commit = txn_alter_trigger_new(
+		on_replace_cluster_update_quorum, replica);
+	if (on_commit == NULL)
+		return -1;
+	txn_stmt_on_commit(stmt, on_commit);
 	return 0;
 }
 

src/box/replication.cc

@@ -448,7 +448,6 @@ replica_clear_id(struct replica *replica)
 		assert(!replica->anon);
 		replica_delete(replica);
 	}
-	box_update_replication_synchro_quorum();
 	box_broadcast_ballot();
 }