Fix recovery conflict in 027_stream_regress.pl.

Fix recovery conflict in 027_stream_regress.pl.

To avoid "ERROR:  canceling statement due to conflict with recovery",
as seen on a couple of slower build farm animals, crank
max_standby_streaming_delay right up.

In passing, adjust a configuration option that accidentally used a
non-standard format (not a problem, but needlessly inconsistent).

Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CA%2BhUKGK65xVqNgsSPyrr2LEwtfUN%3DGfEuQ868hTC-mu0bFG42A%40mail.gmail.com