kernel-install plugin fails with uki layout when removing

[SteelT1]

If the install layout is set to "uki", then when removing a kernel image, it doesn't get removed from the signing database by 91-sbctl.install. Causing the entries for previous kernel versions to stick around.

[ksimuk]

Looks like https://github.com/Foxboron/sbctl/pull/294 broke the functionality, as the file already removed before 91-sbctl.install by 90-uki-copy.install. Removing from the database doesn't require physical file, and should check if record exist in database

Additionally, if mkinitcpio is used https://github.com/Foxboron/sbctl/commit/8e0e68bc0959f4e86ffcde9e8fa3f0a1680bf06e will register and not remove kernels located in /usr/lib/modules/<version>/vmlinuz