Use fipshash in brin_multi test
This fixes some md5() calls that snuck in in
0457109344 after we had
removed them all in
208bf364a9.
Reviewed-by: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://www.postgresql.org/message-id/
a35eaf0f-b19c-7797-e296-
7b7e2adc473e@eisentraut.org