pgsql: Fix broken-FK-detection query in release notes

Fix broken-FK-detection query in release notes

Commits 53af9491a043 and 2d5fe514052a fixed a number of problems with
foreign keys that reference partitioned tables, and a query to detect
already broken FKs was supplied with the release notes for 17.1, 16.5,
15.9, 14.14, 13.17.  However, that query has a bug that causes it to
wrongly report self-referential foreign keys even when they are correct,
so if the user was to drop and rebuild the FKs as indicated, the query
would continue to report them as needing to be repaired.  Here we fix
the query to not have that problem.

Reported-by: Paul Foerster <paul.foerster@gmail.com>
Discussion: https://postgr.es/m/5456A1D0-CD47-4315-9C65-71B27E7A2906@gmail.com
Backpatch-through: 13-17

Branch
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REL_16_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/db54be898a68b8abccf1d5759dcbde9e23c56195

Modified Files
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doc/src/sgml/release-16.sgml | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)