This also makes initrd-cleanup.service explicitly start
initrd-switch-root.service with replace-irreversibly mode, to avoid
systemd-udevd.service being triggered by kernel events and the start
job of initrd-switch-root.service being cancelled.
Follow-ups for 676fb42aae.
Addresses https://github.com/systemd/systemd/pull/37374#issuecomment-2875990471.
This makes things a bit simpler and the build a bit faster, because we don't
have to rewrite files to do the trivial substitution. @rootbindir@ is always in
our internal $PATH that we use for non-absolute paths, so there should be no
functional change.
This will:
* mount all configured filesystems (typically the rootfs on /sysroot)
* reload the configuration to pick up anything from the mounted fs (typically
/sysroot/etc/fstab)
* mount any newly configured filesystems (typically /usr on /sysroot/usr, if
applicable)
* shut-down and clean-up any daemons running in the initramfs (typically udevd)
* switch-root to /sysroot and start the real init
For an example of what files should be included in an initramfs based on this
see
<https://mailman.archlinux.org/pipermail/arch-projects/2013-February/003628.html>.
Cc: Harald Hoyer <harald.hoyer@gmail.com>
Cc: Dave Reisner <d@falconindy.com>
