systemd: remove rudimentary network checking code

Now that we have After=network-online.target added in 35b41f9
NetworkManager is handling this for us and we don't need this
crude network online checking.

systemd/coreos-installer-service

@@ -41,37 +41,6 @@ copy_arg() {
     fi
 }
 
-# Wait for the network to be up by trying to HEAD a URL.
-# There are a few corner cases we have to account for:
-#
-#   - The user gave both ignition_url and image_url
-#       - We need to try both URLs because one could be IP
-#         based and the other could be DNS based. If both are
-#         IP based then we don't need to wait on DNS.
-#   - The user provided only image_url
-#       - This case is simple. Check image_url and continue.
-#   - The user did not provide image_url
-#       - This case implies we are going to contact a remote
-#         service (most likely fedora infra) so we need to
-#         test DNS is working befrore continuing. In this case
-#         we'll check the fedora hotspot globally accessible URL:
-#         http://fedoraproject.org/static/hotspot.txt
-#
-ignition_url="$(karg coreos.inst.ignition_url)"
-image_url="$(karg coreos.inst.image_url)"
-check_urls="${image_url:-http://fedoraproject.org/static/hotspot.txt}"
-if [ -n "${ignition_url}" -a "${ignition_url}" != "skip" ]; then
-    check_urls+=" ${ignition_url}"
-fi
-for check_url in $check_urls; do
-    # We'd like to disable the progress meter but we can only do that
-    # completely with --silent, which also disables status updates. Use
-    # the compact progress bar instead, since at least it's smaller.
-    curl --head --progress-bar --fail \
-        --retry 60 --retry-delay 1 --retry-connrefused \
-        -o /dev/null "${check_url}"
-done
-
 # Get install device
 device="$(karg coreos.inst.install_dev)"
 if [ -z "${device}" ]; then
@@ -85,6 +54,7 @@ fi
 args+=("${device}")
 
 # Fetch the Ignition URL, if any, and cache it locally.
+ignition_url="$(karg coreos.inst.ignition_url)"
 # Ignore "skip" for compatibility
 if [ -n "${ignition_url}" -a "${ignition_url}" != "skip" ]; then
     ignition_file="$(mktemp -t coreos-installer-XXXXXX)"