[YSQL] INSERT ... ON CONFLICT feature is not working for TEMP tables.

[nocaway]

Jira Link: DB-1400
Test cases

Two rows instead of one was inserted in the following test.

postgres=# create temporary table selfconflict (f1 int primary key, f2 int);
CREATE TABLE
postgres=# begin transaction isolation level read committed;
BEGIN
postgres=# insert into selfconflict values (1,1), (1,2) on conflict do nothing;
INSERT 0 2
postgres=# commit;
COMMIT

The CORRECT behavior for TEMP table should have been the following.

test=# create temp table selfconflict (f1 int primary key, f2 int);
CREATE TABLE
test=# begin transaction isolation level read committed;
BEGIN
test=# insert into selfconflict values (1,1), (1,2) on conflict do nothing;
INSERT 0 1
test=# commit;
COMMIT
test=# 
test=# begin transaction isolation level repeatable read;
BEGIN
test=# insert into selfconflict values (2,1), (2,2) on conflict do nothing;
INSERT 0 1
test=# commit;
COMMIT
test=# 
test=# begin transaction isolation level serializable;
BEGIN
test=# insert into selfconflict values (3,1), (3,2) on conflict do nothing;
INSERT 0 1
test=# commit;
COMMIT
test=# 
test=# begin transaction isolation level read committed;
BEGIN
test=# insert into selfconflict values (4,1), (4,2) on conflict(f1) do update set f2 = 0;
ERROR:  ON CONFLICT DO UPDATE command cannot affect row a second time
HINT:  Ensure that no rows proposed for insertion within the same command have duplicate constrained values.
test=# commit;
ROLLBACK
test=# 
test=# begin transaction isolation level repeatable read;
BEGIN
test=# insert into selfconflict values (5,1), (5,2) on conflict(f1) do update set f2 = 0;
ERROR:  ON CONFLICT DO UPDATE command cannot affect row a second time
HINT:  Ensure that no rows proposed for insertion within the same command have duplicate constrained values.
test=# commit;
ROLLBACK
test=# 
test=# begin transaction isolation level serializable;
BEGIN
test=# insert into selfconflict values (6,1), (6,2) on conflict(f1) do update set f2 = 0;
ERROR:  ON CONFLICT DO UPDATE command cannot affect row a second time
HINT:  Ensure that no rows proposed for insertion within the same command have duplicate constrained values.
test=# commit;
ROLLBACK
test=# 
test=# select * from selfconflict order by f1;
 f1 | f2 
----+----
  1 |  1
  2 |  1
  3 |  1
(3 rows)

[jasonyb]

Appears to work on master e0629f3, fastdebug, almalinux 8, gcc11