mxgrub: Do not add Intel μ-code updates for early loading

*sauterelles* experienced frequent hangs since the boot on August 27th,
2023. Due to merge/pull request [*Create microcode update archives and
load them in GRUB*][1] newer microcode 0x5003604 was loaded early.

    [    0.000000] microcode: microcode updated early to revision 0x5003604, date = 2023-03-17
    [    0.000000] Linux version 5.15.86.mx64.443 (root@theinternet.molgen.mpg.de) (gcc (GCC) 10.4.0, GNU ld (GNU Binutils) 2.37) #1 SMP Thu Jan 5 12:40:04 CET 2023

History:

    $ last reboot | head -7
    reboot   system boot  5.15.77.mx64.440 Wed Oct  4 12:20   still running
    reboot   system boot  5.15.77.mx64.440 Wed Oct  4 10:33 - 12:19  (01:45)
    reboot   system boot  5.15.77.mx64.440 Mon Oct  2 11:00 - 12:19 (2+01:18)
    reboot   system boot  5.15.86.mx64.443 Mon Sep 11 11:42 - 12:19 (23+00:36)
    reboot   system boot  5.15.86.mx64.443 Sun Aug 27 19:28 - 11:23 (14+15:54)
    reboot   system boot  5.15.86.mx64.443 Tue Feb  7 11:39 - 11:23 (215+22:43)
    reboot   system boot  5.15.77.mx64.440 Wed Dec 14 23:05 - 11:32 (54+12:26)

As the identical file servers * epizootie*, *plage*, *rabies*, *lyssa*,
and *grele*, that haven’t been rebooted, do not show any problems, the
hangs might be due to the microcode updates.

Therefore, do not load Intel microcode updates early, until the issue is
better understood.

[1]: #342

mxgrub/mxgrub

@@ -249,7 +249,7 @@ sub update_grub_cfg {
 
 	for my $label (@MARIUX) {
 		my $image=label_to_image($label);
-		$kernellist.="\tmenuentry \"$label\" --unrestricted { save_env chosen ; linux /boot/$image root=LABEL=root $KERNEL_PARAMETER ; initrd /boot/amd-ucode.img /boot/intel-ucode.img /boot/grub/initramfs.igz }\n";
+		$kernellist.="\tmenuentry \"$label\" --unrestricted { save_env chosen ; linux /boot/$image root=LABEL=root $KERNEL_PARAMETER ; initrd /boot/amd-ucode.img /boot/grub/initramfs.igz }\n";
 	}
 
 	my $GRUB_CFG_NEW=<<"EOF";
@@ -267,10 +267,10 @@ insmod all_video
 
 if [ -e /etc/local/USB.usb ]; then
 	set default="mariuxUSB"
-	menuentry "mariuxUSB" --unrestricted { save_env chosen ; linux /boot/bzImage.x86_64 root=LABEL=rootusb rootdelay=5 $KERNEL_PARAMETER ; initrd /boot/amd-ucode.img /boot/intel-ucode.img /boot/grub/initramfs.igz }
+	menuentry "mariuxUSB" --unrestricted { save_env chosen ; linux /boot/bzImage.x86_64 root=LABEL=rootusb rootdelay=5 $KERNEL_PARAMETER ; initrd /boot/amd-ucode.img /boot/grub/initramfs.igz }
 else
 
-menuentry "$MARIUX_DEFAULT" --unrestricted { set chosen="$submenu>$MARIUX_DEFAULT" ; save_env chosen ; linux /boot/bzImage.x86_64 root=LABEL=root $KERNEL_PARAMETER ; initrd /boot/amd-ucode.img /boot/intel-ucode.img /boot/grub/initramfs.igz }
+menuentry "$MARIUX_DEFAULT" --unrestricted { set chosen="$submenu>$MARIUX_DEFAULT" ; save_env chosen ; linux /boot/bzImage.x86_64 root=LABEL=root $KERNEL_PARAMETER ; initrd /boot/amd-ucode.img /boot/grub/initramfs.igz }
 
 submenu "$submenu" --unrestricted {
 $kernellist