don't update default boot entry too early

Description of problem:
Default boot entry should be updated only when kernel and initramdisk are in place. Atm. it's updated optimistically before ramdisk creation which can lead to boot problems (for example Bug 2084197). dracut or other script should be given a chance to prevent change to default boot entry if something went wrong.

Version-Release number of selected component (if applicable):
grub2-common-2.06-46.el9_1.2.noarch

Actual results:
default boot entry is updated before ramdisk creation

Expected results:
default boot entry is updated only if ramdisk has been successfully built