web: removed duplicate host headers

Fixes: https://github.com/jitsi/docker-jitsi-meet/issues/568

web/rootfs/defaults/meet.conf

@@ -81,12 +81,10 @@ location /etherpad/ {
     proxy_http_version 1.1;
     proxy_set_header Upgrade $http_upgrade;
     proxy_set_header Connection 'upgrade';
-    proxy_set_header Host $host;
     proxy_cache_bypass $http_upgrade;
 
     proxy_pass {{ .Env.ETHERPAD_URL_BASE }}/;
     proxy_set_header X-Forwarded-For $remote_addr;
     proxy_buffering off;
-    proxy_set_header Host {{ .Env.XMPP_DOMAIN }};
 }
 {{ end }}