Backport the qcow2 ubuntu-core image generation for LXD support.

debian/changelog

@@ -1,3 +1,9 @@
+livecd-rootfs (24.04.73) UNRELEASED; urgency=medium
+
+  * Build qcow2 images for ubuntu-core LXD support (LP: #2072759).
+
+ -- Łukasz 'sil2100' Zemczak <lukasz.zemczak@ubuntu.com>  Thu, 11 Jul 2024 13:15:43 +0200
+
 livecd-rootfs (24.04.72) noble; urgency=medium
 
   [ Heinrich Schuchardt ]

live-build/auto/build

@@ -37,6 +37,11 @@ if [ "${IMAGEFORMAT:-}" = "ubuntu-image" ] \
 		#  we should be supporting more than one for models that
 		#  define those.
 		mv output/*.img "$PREFIX".img
+		# For standard, non-platform-specific core images, prepare a
+		# qcow2 image as well for LXD consumption.
+		if [ -z "${SUBARCH:-}" ]; then
+			convert_to_qcow2 "$PREFIX".img "$PREFIX".qcow2
+		fi
 		xz -0 -T4 "$PREFIX".img
 		mv output/seed.manifest "$PREFIX".manifest