Downgrading rootfs from bookworm to bullseye

During performing sanity checks on Firecracker-containerd, the AMD ec2 instance got failed.
It is due to panicking of kernel and systemd causes segmentation fault while pulling an image.
Then we downgraded the Debian version of rootfs from bokworm to bullseye to work.

Signed-off-by: Vaishnavi Vejella <[email protected]>

Author: Vejella

tools/image-builder/Makefile

@@ -46,7 +46,7 @@ define run_debootstrap =
 	debootstrap \
 		--variant=minbase \
 		--include=$(subst $(SPACE),$(COMMA),$(PACKAGES))\
-		bookworm \
+		bullseye \
 		"$(WORKDIR)" $(DEBMIRROR)
 	rm -rf "$(WORKDIR)/var/cache/apt/archives" \
 	       "$(WORKDIR)/usr/share/doc" \