adjust name for upstream in lb

Signed-off-by: Tuan-Dat Tran <tuan-dat.tran@tudattr.dev>

roles/loadbalancer/templates/nginx.conf.j2

@@ -16,15 +16,16 @@ stream {
 }
 
 http {
-  upstream k3s_servers {
-      {% for ip in k3s_server_ips %}
-      server {{ ip }};
-      {% endfor %}
+  upstream k3s_servers_http {
+    least_conn;
+    {% for ip in k3s_server_ips %}
+    server {{ ip }};
+    {% endfor %}
   }
 
   server {
     location / {
-        proxy_pass http://k3s_servers;
-      }
+      proxy_pass http://k3s_servers_http;
+    }
   }
 }