GUACAMOLE-1757: Ensure SSO provider list is added to login UI only once.

extensions/guacamole-auth-sso/modules/guacamole-auth-sso-ssl/src/main/resources/html/sso-provider-ssl.html

@@ -1,4 +1,4 @@
-<meta name="after-children" content=".login-ui .sso-provider-list:last-child">
+<meta name="after-children" content=".login-ui .sso-provider-list">
 <li class="sso-provider sso-provider-ssl"><a guac-ssl-auth href="">{{
     'LOGIN.NAME_IDP_SSL' | translate
 }}</a></li>