Merge grub-pc-removal-cherrypick-focal into focal [a=patviafore] [r=codyshepherd,philroche]

Cherry-pick grub-pc removal.

Azure wants the grub-pc change by the end of the month, and the SRU process will not be finished by then. Cherry-picking the change to our team fork while waiting for the actual change to land.

MP: https://code.launchpad.net/~patviafore/livecd-rootfs/+git/livecd-rootfs/+merge/394431

live-build/auto/config

@@ -775,8 +775,7 @@ case $PROJECT in
 				add_package install grub-pc
 				;;
 			amd64)
-				add_package install grub-pc-bin
-				add_package install grub-efi-amd64-signed
+				add_package install grub-pc
 				add_package install shim-signed
 				;;
 		esac

live-build/ubuntu-cpc/hooks.d/base/disk-image-ppc64el.binary

@@ -33,6 +33,7 @@ install_grub() {
     chroot mountpoint apt-get -qqy update
     chroot mountpoint apt-get -qqy install grub-ieee1275
     chroot mountpoint apt-get -qqy remove --purge grub-legacy-ec2
+    chroot mountpoint apt-get autoremove --purge --assume-yes
 
     # set the kernel commandline to use hvc0
     mkdir -p mountpoint/etc/default/grub.d

live-build/ubuntu-cpc/hooks.d/base/disk-image-uefi.binary

@@ -97,11 +97,13 @@ install_grub() {
             efi_target=arm-efi
             ;;
         amd64)
-            chroot mountpoint apt-get install -qqy grub-efi-amd64-signed shim-signed
+            chroot mountpoint apt-get install -qqy grub-pc shim-signed
             efi_target=x86_64-efi
             ;;
     esac
 
+    chroot mountpoint apt-get autoremove --purge --assume-yes
+
     # This call to rewrite the debian package manifest is added here to capture
     # grub-efi packages that otherwise would not make it into the base
     # manifest. filesystem.packages is moved into place via symlinking to

live-build/ubuntu-cpc/hooks.d/base/disk-image.binary

@@ -136,6 +136,7 @@ fi
 if [ "$ARCH" = "s390x" ]; then
     # Do ZIPL install bits
     chroot mountpoint apt-get -qqy install s390-tools sysconfig-hardware
+    chroot mountpoint apt-get autoremove --purge --assume-yes
 
     # Write out cloudy zipl.conf for future kernel updates
     cat << EOF > mountpoint/etc/zipl.conf

live-build/ubuntu-cpc/hooks.d/base/wsl.binary

@@ -35,6 +35,7 @@ cp -a rootfs.dir $rootfs_dir
 setup_mountpoint $rootfs_dir
 
 env DEBIAN_FRONTEND=noninteractive chroot $rootfs_dir apt-get -y -qq install ubuntu-wsl
+env DEBIAN_FRONTEND=noninteractive chroot $rootfs_dir apt-get autoremove --purge --assume-yes
 
 create_manifest $rootfs_dir livecd.ubuntu-cpc.wsl.rootfs.manifest
 teardown_mountpoint $rootfs_dir