tests(packer): rewrite the way to build the tests images.

tests/packer/clean.sh

@@ -56,9 +56,6 @@ clean_apt() {
 clean_pacman() {
 	_msg "Cleaning pacman cache"
 	pacman -Syu --noconfirm
-	pacman -Qdtq | while IFS='' read -r pkg; do
-		pacman -Rsccn --noconfirm "$pkg"
-	done
 	pacman -Scc --noconfirm
 }
 
@@ -136,10 +133,6 @@ trim() {
 		truncate --size=0 /swap/swapfile
 	fi
 
-	# _msg "Fill root filesystem with 0 to reduce box size"
-	# dd if=/dev/zero of=/EMPTY bs=1M || true
-	# rm -f /EMPTY
-
 	# Block until the empty file has been removed, otherwise, Packer will
 	# try to kill the box while the disk is still full and that is bad.
 	sync