re: postgres_fdw hint messages

>The postgres_fdw tests contain this (as amended by patch 0001):

>ALTER SERVER loopback_nopw OPTIONS (ADD password 'dummypw');
>ERROR: invalid option "password"
>HINT: Valid options in this context are: service, passfile,
>channel_binding, connect_timeout, dbname, host, hostaddr, port, options,
>application_name, keepalives, keepalives_idle, keepalives_interval,
>keepalives_count, tcp_user_timeout, sslmode, sslcompression, sslcert,
>sslkey, sslrootcert, sslcrl, sslcrldir, sslsni, requirepeer,
>ssl_min_protocol_version, ssl_max_protocol_version, gssencmode,
>krbsrvname, gsslib, target_session_attrs, use_remote_estimate,
>fdw_startup_cost, fdw_tuple_cost, extensions, updatable, truncatable,
>fetch_size, batch_size, async_capable, parallel_commit, keep_connections

>This annoys developers who are working on libpq connection options,
>because any option added, removed, or changed causes this test to need
>to be updated.

>It's also questionable how useful this hint is in its current form,
>considering how long it is and that the options are in an
>implementation-dependent order.

>Possible changes:

>- Hide the hint from this particular test (done in the attached patches).+1