Remove tftp healthcheck from ironic-pxe image

This is failing downstream because the installed curl-minimal does not
have tftp support. This healthcheck likely doesn't add much value
since dnsmasq is a self-contained tool which will be bound to the port
if it is running.

The healthcheck for dnsmasq as a DHCP server has already been
removed[1].

The alternative to removing this check is to ensure the 'curl' package
is installed instead of 'curl-minimal'.

[1] https://review.opendev.org/c/openstack/tripleo-common/+/799946

Change-Id: I126b997608edb217b0fbf40f4228d0f0af689b0e

healthcheck/ironic-pxe

@@ -8,9 +8,6 @@ if grep "/httpd " /run_command 2>/dev/null ; then
     protocol=http
     path=
 else
-    bind_host=$(hiera ironic::pxe::tftp_bind_host -c /etc/puppet/hiera.yaml)
-    bind_port=69
-    protocol=tftp
-    path=map-file
+    exit 0
 fi
 healthcheck_curl ${protocol}://${bind_host}:${bind_port}/${path}