Revert "Set the proxying header for the LDAP auth service."

This reverts commit 7885e91e.

snippets/ldap-auth.conf

@@ -4,7 +4,6 @@ location = /validate {
   proxy_pass                        https://auth.shore.co.il/validate;
   proxy_http_version                1.1;
   include                           snippets/proxy-ssl.conf;
-  include                           snippets/proxy-headers.conf;
   internal;
   proxy_pass_request_body           off;
   proxy_set_header Content-Length   "";