udev: udev rules cleanup

udev: udev rules cleanup

Remove executable path detection in udev rules and use sbindir that
is configured, but still provide the original functionality by means
of 'configure --enable-udev-rule-exec-detection'.

Normally, the exec path for the tools called in udev rules should
not differ from the sbindir used, however, there are cases this is
necessary. For example different environments could be assembled
in a way that these path differ for some reason (distribution installer,
initrd ...).

This functionality is kept for compatibility only. Any environment
moving the binaries around and using different paths should be fixed
eventually!