Comment 0 for bug 1901553

[Impact]

 * Sometimes it is not obvious why initrdless boot is generated; when is it attempted; and when it fails and boots with initrd.

 * Improve UX by leaving breadcrumbs and emit messages about initrdless boot, in more places

[Test Case]

 * Boot system with initrdless boot (such as modern AWS images)
 * Upgrade to new grub package
 * Reboot

 * Observe the following:

 1. Upon `sudo update-grub`, message is emitted that initrdless boot will be attempted

 2. Inspecting /boot/grub/grub.cfg, there are comments that initrdless boot will be attempted

 3. Inspecting console log, there are echo message from grub about attempting initrdless boot.

 * Install linux-generic kernel flavour; and remove aws kernel flavour, reboot.
 * Observe in the console log

 1. There should be message about attempting initrdless boot
 2. kernel panic
 3. message about initrdless boot failing and attempting to boot with initrd

[Regression Potential]

 * This change adds a few more user visible message, without translations. The actual behaviour that is happening is unchanged. This simply better notifies users about what is happening, and can be inspected interactively, statically, and from boot logs.

[Other Info]

 * CPC requested these UX improvements, as there have been concerns that users are failing to discover why initrdless boot is happening; or failing; and how to effect it.