Updates don't enable new kernel, boot parameters without effect

### What Happened?

I ran all updates, but it's always the old kernel which is booted. The newest is installed, but not selected. Also, when I add boot parameters to `/etc/default/grub` they don't end up in grub and thus show no effect.

Don't know if this is the right repo for system update issues?

### Steps to Reproduce

Also see https://github.com/elementary/gala/issues/2023#issuecomment-2323460734

### Expected Behavior

New kernel should be loaded, boot parameters should be applied.

### OS Version

8.x (Early Access)

### Software Version

Latest release (I have run all updates)

### Log Output

```shell
$ uname -a
Linux XinkPad280 6.8.0-40-generic #40-Ubuntu SMP PREEMPT_DYNAMIC Fri Jul 5 10:34:03 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux
$ ls -la /boot/
insgesamt 186588
drwxr-xr-x 5 root root 4096 Sep 12 07:39 .
drwxr-xr-x 21 root root 4096 Sep 12 10:40 ..
-rw-r--r-- 1 root root 287442 Jul 5 10:31 config-6.8.0-40-generic
-rw-r--r-- 1 root root 287493 Aug 13 12:20 config-6.8.0-44-generic
drwx------ 3 root root 4096 Jan 1 1970 efi
drwxr-xr-x 2 root root 4096 Sep 12 07:39 grub
lrwxrwxrwx 1 root root 27 Sep 11 17:58 initrd.img -> initrd.img-6.8.0-44-generic
-rw-r--r-- 1 root root 71222640 Sep 2 10:35 initrd.img-6.8.0-40-generic
-rw-r--r-- 1 root root 71193861 Sep 11 17:58 initrd.img-6.8.0-44-generic
lrwxrwxrwx 1 root root 27 Sep 12 07:38 initrd.img.old -> initrd.img-6.8.0-40-generic
drwx------ 2 root root 16384 Aug 13 19:42 lost+found
-rw------- 1 root root 9058665 Jul 5 10:31 System.map-6.8.0-40-generic
-rw------- 1 root root 9061992 Aug 13 12:20 System.map-6.8.0-44-generic
lrwxrwxrwx 1 root root 24 Sep 11 17:58 vmlinuz -> vmlinuz-6.8.0-44-generic
-rw------- 1 root root 14944648 Jul 5 11:12 vmlinuz-6.8.0-40-generic
-rw------- 1 root root 14956936 Aug 13 12:22 vmlinuz-6.8.0-44-generic
lrwxrwxrwx 1 root root 24 Sep 12 07:38 vmlinuz.old -> vmlinuz-6.8.0-40-generic

No errors.
```

### Hardware Info

Lenovo Thinkpad X280, secure boot enabled