Revert "loadbalancer: use TCP checks for Spice"

This patch breaks HAproxy to start:
[ALERT] 230/085911 (53231) : parsing [/etc/haproxy/haproxy.cfg:235] :
'http-check' only supports 'disable-on-404', 'send-state', 'expect'.

This reverts commit 755851c93889b92e10a9dbddc6f591a7bc6ec01a.