PostgreSQL tests use pg_temp only. pg_temp is never searched for FTS
objects, so creating then altering an FTS configuration will not work
because PostgreSQL will not be able to find the FTS configuration it
just created.
Instead, we explicitly refer to the FTS objects with their full name
including their prefix, which makes PostgreSQL able to find the object.
This is only needed for tests.
See: https://stackoverflow.com/a/31095452/2347617
See: https://www.postgresql.org/message-id/15191.1208975632@sss.pgh.pa.us
