Creating a separate /boot partition is desirable in some cases[1].
This change detects if /boot is a partition, and ensures that the
kernel/ramdisk paths are correct in either case. This is applied to
all BLS entries files, whether they were generated by the previous
grub2-mkconfig call or in the source image.
This means the rhel9 specific workaround can be removed since all
paths are now normalised at this stage.
[1] https://review.opendev.org/c/openstack/tripleo-image-elements/+/846807
Change-Id: I62120ec8c65876e451532d2654d37435eb3606a6
Resolves: rhbz#2101514
f118649738