Update triton one nginx config

Delay resolution of the proxy until the first request. This allows
the nginx instance to start when using `standalone-dev-nginx.conf`
but perhaps with a provider other than triton one.

Without this, nginx errors out with the following log line:

    2021/09/16 13:57:36 [emerg] 5077#0: host not found in upstream "YOUR_SERVER.rpcpool.com" in triton-one-virt-server-config.conf:59

Author: Jeff Schroeder

doc/nginx-configs/triton-one-virt-server-config.conf

@@ -12,13 +12,17 @@
 server {
     listen 7902;
 
+    # e.g: companyname1.rpcpool.com
+    set $upstream_host YOUR_SERVER;
+    set $auth_token REPLACE_ME_WITH_YOUR_AUTH_TOKEN;
+
     location / {
         try_files /nonexistent-used-for-try-testing @$http_upgrade;
     }
 
     location @websocket {
         # With authentication
-        proxy_pass https://YOUR_SERVER.rpcpool.com/REPLACE_ME_WITH_YOUR_AUTH_TOKEN$request_uri;
+        proxy_pass https://$upstream_host/$auth_token$request_uri;
 
         # Without authentication, i.e. IP allow listed
         #proxy_pass https://YOUR_SERVER.rpcpool.com$request_uri;
@@ -33,10 +37,10 @@ server {
 
     location @ {
         # With authentication
-        proxy_pass https://YOUR_SERVER.rpcpool.com/REPLACE_ME_WITH_YOUR_AUTH_TOKEN$request_uri;
+        proxy_pass https://$upstream_host/$auth_token$request_uri;
 
         # Without authentication, i.e. IP allow listed
-        #proxy_pass https://YOUR_SERVER.rpcpool.com$request_uri;
+        #proxy_pass https://$upstream_host$request_uri;
         proxy_http_version 1.1;
         proxy_set_header Host $proxy_host;
         proxy_set_header Connection "";
@@ -54,12 +58,16 @@ server {
 server {
     listen 7802;
 
+    # e.g: companyname1.rpcpool.com
+    set $upstream_host YOUR_SERVER;
+    set $auth_token REPLACE_ME_WITH_YOUR_AUTH_TOKEN;
+
     location / {
         # With authentication
-        proxy_pass https://YOUR_SERVER.rpcpool.com/REPLACE_ME_WITH_YOUR_AUTH_TOKEN;
+        proxy_pass https://$upstream_host/$auth_token;
 
         # Without authentication, i.e. IP allow listed
-        #proxy_pass https://YOUR_SERVER.rpcpool.com;
+        #proxy_pass https://$upstream_host;
         proxy_http_version 1.1;
         proxy_set_header Host $proxy_host;
         # websocket requirements