Trigger based audit does not work on pg_dist_placement

Trigger based audit enabled on Citus metadata table using superuser do not create any audit records.

`create or replace function pg_dist_placement_audit_info() returns trigger
as
$pg_dist_placement_audit$
begin
if (TG_OP = 'DELETE') THEN
insert into pg_dist_placement_audit SELECT 'D', now(), user, OLD.*;
elsif (TG_OP = 'UPDATE') THEN
insert into pg_dist_placement_audit SELECT 'U_OLD', now(), user, OLD.*;
insert into citus.pg_dist_placement_audit SELECT 'U_NEW', now(), user, NEW.*;
elsif (TG_OP = 'INSERT') THEN
insert into pg_dist_placement_audit SELECT 'I', now(), user, NEW.*;
end if;
return null;
end;
$pg_dist_placement_audit$
language plpgsql;
`

`create trigger pg_dist_placement_audit_trigger
after insert or update or delete on pg_dist_placement
for each row
execute procedure pg_dist_placement_audit_info();`

Audit table “pg_dist_placement_audit” is never populated with audit records when there is a DML in the pg_dist_placement table following creating/dropping of a distributed table.
However, this works perfectly fine while manually performing DML operations in “pg_dist_placement” table.

Start by reproducing the trigger setup shown in the issue, then perform DML on pg_dist_placement after creating and dropping a distributed table, comparing it with manual DML. Done means the trigger reliably creates the expected audit records for these metadata-table changes.

Written by the indexing model from the issue text.