cmd-build: drop composefs logic

All the settings in all image.yaml files in the fedora-coreos-config
and rhel-coreos-config repos have this set to `false` so it's not being
used today.

Also we are planning to remove this build path in the future in favor of
building via container tools, so let's just drop this for now.

Author: dustymabe

src/cmd-build

@@ -324,15 +324,6 @@ fi
 if [ ! -f "${workdir}"/builds/builds.json ] && [ ! -f "${fetch_stamp}" ] ; then
     fatal "Must fetch before building"
 fi
-composefs="$(jq -r .composefs < "${image_json}")"
-case "${composefs}" in
-    false)
-    ;;
-    true)
-        ostree config --repo="${tmprepo}" set ex-integrity.composefs "true"
-    ;;
-    *) fatal "Unhandled composefs setting: ${composefs}" ;;
-esac
 
 # --cache-only is here since `fetch` is a separate verb
 # shellcheck disable=SC2086