default.pa: remove X11 module examples

default.pa: remove X11 module examples

Loading X stuff from default.pa is a bad idea, since it doesn't work
if there are multiple X sessions, or PulseAudio is started outside the
X session. Since it's a bad idea, don't encourage it by including
examples that do so.

I also removed the sample loading examples. I don't think the examples
are particularly useful, since nothing uses the loaded samples once
module-x11-bell is removed from the configuration.

BugLink: https://bugs.freedesktop.org/show_bug.cgi?id=93109