ATTACH PARTITION: Don't match a PK with a UNIQUE constraint

When matching constraints in AttachPartitionEnsureIndexes() we weren't
testing the constraint type, which could make a UNIQUE key lacking a
not-null constraint incorrectly satisfy a primary key requirement.  Fix
this by testing that the constraint types match.  (Other possible
mismatches are verified by comparing index properties.)

Discussion: https://postgr.es/m/202402051447.wimb4xmtiiyb@alvherre.pgsql

src/backend/commands/tablecmds.c

@@ -19550,6 +19550,11 @@ AttachPartitionEnsureIndexes(List **wqueue, Relation rel, Relation attachrel)
 					/* no dice */
 					if (!OidIsValid(cldConstrOid))
 						continue;
+
+					/* Ensure they're both the same type of constraint */
+					if (get_constraint_type(constraintOid) !=
+						get_constraint_type(cldConstrOid))
+						continue;
 				}
 
 				/* bingo. */