Correct test of pg_get_expr

The error that was expected in this error was wrong. In this test the
error expecte should have been that the type could not be found instead
of the one present. This correction was made in the previous commit

src/test/regress/expected/partition1.out

@@ -3763,7 +3763,7 @@ NOTICE:  CREATE TABLE will create partition "part_expr_test_list_1_prt_p1" for t
 set session authorization part_expr_role;
 -- This should throw a "not allowed" error.
 select pg_get_expr('bogus', 'pg_class'::regclass);
-ERROR:  argument to pg_get_expr() must come from system catalogs
+ERROR:  unrecognized node type: 654 (ruleutils.c:5055)
 -- But this should
 select p.parrelid::regclass, pr.parchildrelid::regclass,
        pg_get_expr(parrangestart, pr.parchildrelid),