Make scriptlets non-failing and skip udevadm reload if no udev
sysctl, binfmt, and other rules are collected from multiple packages
and we don't want to see a report that systemd %triggerin failed.
So let's not silence the output, but use "|| :" to the trigger is
not reported as failed.
Also, adjust the udevadm check. In containers udevd might not be
running, even if systemd is, and we'd get:
Failed to send reload request: No such file or directory