initramfs generation needs to be streamlined

[dmcilvaney]

Is your feature request related to a problem? Please describe.
The current mkinitrd is archaic. We should be directly invoking dracut to generate an initramfs.

Describe the solution you'd like
Refactor all code that calls mkinitrd to instead call dracut, better use the existing configuraiton options of dracut (ie hostonly, etc.).

Additional context
Add any other context or screenshots about the feature request here.

[LaszloGombos]

Some recent commits seems to be increasing the usage of mkinitrd - #7358

PR commit switches to use the default way mkinitrd to build / update the initrd img for DM-Verity, instead of using dracut to build another new initramfs img

CC @liulanze