Fix oversight in FindTriggerIncompatibleWithInheritance.

This function is called from ATExecAttachPartition/ATExecAddInherit,
which prevent tables with row-level triggers with transition tables from
becoming partitions or inheritance children, to check if there is such a
trigger on the given table, but failed to check if a found trigger is
row-level, causing the caller functions to needlessly prevent a table
with only a statement-level trigger with transition tables from becoming
a partition or inheritance child.  Repair.

Oversight in commit 501ed02cf.

Author: Etsuro Fujita <etsuro.fujita@gmail.com>
Discussion: https://postgr.es/m/CAPmGK167mXzwzzmJ_0YZ3EZrbwiCxtM1vogH_8drqsE6PtxRYw%40mail.gmail.com
Backpatch-through: 13

src/backend/commands/trigger.c

@@ -2120,6 +2120,8 @@ FindTriggerIncompatibleWithInheritance(TriggerDesc *trigdesc)
 		{
 			Trigger    *trigger = &trigdesc->triggers[i];
 
+			if (!TRIGGER_FOR_ROW(trigger->tgtype))
+				continue;
 			if (trigger->tgoldtable != NULL || trigger->tgnewtable != NULL)
 				return trigger->tgname;
 		}

src/test/regress/expected/triggers.out

@@ -2930,6 +2930,10 @@ NOTICE:  trigger = child3_delete_trig, old table = (42,CCC)
 -- copy into parent sees parent-format tuples
 copy parent (a, b) from stdin;
 NOTICE:  trigger = parent_insert_trig, new table = (AAA,42), (BBB,42), (CCC,42)
+-- check detach/reattach behavior; statement triggers with transition tables
+-- should not prevent a table from becoming a partition again
+alter table parent detach partition child1;
+alter table parent attach partition child1 for values in ('AAA');
 -- DML affecting parent sees tuples collected from children even if
 -- there is no transition table trigger on the children
 drop trigger child1_insert_trig on child1;
@@ -3127,6 +3131,10 @@ NOTICE:  trigger = parent_insert_trig, new table = (AAA,42), (BBB,42), (CCC,42)
 create index on parent(b);
 copy parent (a, b) from stdin;
 NOTICE:  trigger = parent_insert_trig, new table = (DDD,42)
+-- check disinherit/reinherit behavior; statement triggers with transition
+-- tables should not prevent a table from becoming an inheritance child again
+alter table child1 no inherit parent;
+alter table child1 inherit parent;
 -- DML affecting parent sees tuples collected from children even if
 -- there is no transition table trigger on the children
 drop trigger child1_insert_trig on child1;

src/test/regress/sql/triggers.sql

@@ -2038,6 +2038,11 @@ BBB	42
 CCC	42
 \.
 
+-- check detach/reattach behavior; statement triggers with transition tables
+-- should not prevent a table from becoming a partition again
+alter table parent detach partition child1;
+alter table parent attach partition child1 for values in ('AAA');
+
 -- DML affecting parent sees tuples collected from children even if
 -- there is no transition table trigger on the children
 drop trigger child1_insert_trig on child1;
@@ -2257,6 +2262,11 @@ copy parent (a, b) from stdin;
 DDD	42
 \.
 
+-- check disinherit/reinherit behavior; statement triggers with transition
+-- tables should not prevent a table from becoming an inheritance child again
+alter table child1 no inherit parent;
+alter table child1 inherit parent;
+
 -- DML affecting parent sees tuples collected from children even if
 -- there is no transition table trigger on the children
 drop trigger child1_insert_trig on child1;