The integration tests use /etc/rc.d/init.d if it exists
or falls back to /etc/init.d,
while the mkosi.build.chroot script dereferenced /etc/init.d.
This produces inconsistent results, as sometimes an image can be made
that has systemd built to expect /etc/init.d but /etc/rc.d/init.d
also exists.
- Use mkosi.images/ instead of mkosi.presets/
- Use the .chroot suffix to run scripts in the image
- Use BuildSources= match for the kernel build
- Move 10-systemd.conf to mkosi.conf and rely on mkosi.local.conf
for local configuration
