Revert "Dynamically generate Ubuntu live options"

This reverts commit 4ed123f34fa084fa6c92baef07eecfe3418b2a93.

roles/netbootxyz/templates/menu/live-ubuntu.ipxe.j2

@@ -6,9 +6,9 @@ goto ${menu} ||
 set os Ubuntu Live
 menu ${os}
 item --gap ${os} Versions
-{% for item in releases.ubuntu.versions %}
-item {{ item.code_name }} ${space} ${os} {{ item.name }}
-{% endfor %}
+item jammy ${space} ${os} 22.04
+item focal ${space} ${os} 20.04
+item bionic ${space} ${os} 18.04
 choose live_version || goto live_exit
 menu ${os} ${live_version}
 item --gap ${os} Flavors