message: test: update pg_constraint test to actually assert on results
diff: query IIIIII nosort pg_constraint
  SELECT * FROM pg_constraint
  -query IIIIII nosort pg_constraint
  +statement ok
  +create table a (id int , primary key (id));
  +
  +statement ok
  +create table b (id int , foreign_a int, foreign key (foreign_a) references a);
  +
  +statement ok
  +insert into a (id) values (0);
  +
  +statement ok
  +insert into b (id, foreign_a) VALUES (0, 0);
  +
  +query IIIIIIIIIIIIIIIIIIIIIIIII
  SELECT * FROM pg_catalog.pg_constraint
  +----
  +866000000 PRIMARY KEY(id) 1 p false false true 866 0 0 0 0 NULL NULL NULL true 0 false [0] NULL NULL NULL NULL NULL NULL
  +866000001 NOT NULL 1 x false false true 866 0 0 0 0 NULL NULL NULL true 0 false [0] NULL NULL NULL NULL NULL NULL
  +863000000 FOREIGN KEY (foreign_a) REFERENCES a(id) 1 f false false true 863 0 0 0 0 NULL NULL NULL true 0 false [1] NULL NULL NULL NULL NULL NULL
  