Default to log_lock_waits=on

Default to log_lock_waits=on

If someone is stuck behind a lock for more than a second, that is
almost always a problem that is worth a log entry.

Author: Laurenz Albe <laurenz.albe@cybertec.at>
Reviewed-By: Michael Banck <mbanck@gmx.net>
Reviewed-By: Robert Haas <robertmhaas@gmail.com>
Reviewed-By: Christoph Berg <myon@debian.org>
Reviewed-By: Stephen Frost <sfrost@snowman.net>
Discussion: https://postgr.es/m/b8b8502915e50f44deb111bc0b43a99e2733e117.camel%40cybertec.at