fix(dracut): enable hostonly_cmdline in hostonly mode again

fix(dracut): enable hostonly_cmdline in hostonly mode again

A fresh Ubuntu 26.04 installation with a RAID 1 fails to boot due to not
assembling the RAID, because it neither sets `rd.auto` nor includes the
cmdline (with `rd.md.uuid` set).

The documentation for `hostonly_cmdline` says:

> If **hostonly="yes"** and this option is not configured, it's
> automatically set to "yes".

When `hostonly=yes` was made the default, `hostonly_cmdline` was not set
to `yes` any more in the default case.

Bug-Ubuntu: https://launchpad.net/bugs/2144948
Fixes: 24fb4c28538b ("feat(dracut): make hostonly the default")