fix: ensure relation destroy ops are sorted

As for offers in the prior commit, this ensures that relations can be
forcibly removed without encountering errors based on transaction
operations with removals before updates.

state/relation.go

@@ -375,7 +375,10 @@ func (op *DestroyRelationOperation) internalDestroy() (ops []txn.Op, err error)
 	} else if op.FatalError(err) {
 		return nil, err
 	}
-	return append(ops, destroyOps...), nil
+
+	ops = append(ops, destroyOps...)
+	sortRemoveOpsLast(ops)
+	return ops, nil
 }
 
 // destroyOps returns the operations necessary to destroy the relation, and