Fix env substitute issue in websocket docker setup (#3296)

* fix websocket connection issue in docker makeplane/plane#3195

* fix websocket connection issue for local env with removing from the prod nginx conf template makeplane/plane#319

* fix env substitution issue  of proxy_set_header makeplane/plane#3196

* review fixes

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Co-authored-by: Manish Gupta <manish@mgupta.me>

nginx/env.sh

@@ -1,4 +1,6 @@
 #!/bin/sh
 
+export dollar="$"
+export http_upgrade="http_upgrade"
 envsubst < /etc/nginx/nginx.conf.template > /etc/nginx/nginx.conf
 exec nginx -g 'daemon off;'

nginx/nginx.conf.dev

@@ -19,7 +19,7 @@ http {
         location / {
             proxy_pass http://web:3000/;
             proxy_http_version 1.1;
-            proxy_set_header Upgrade $http_upgrade;
+            proxy_set_header Upgrade ${dollar}http_upgrade;
             proxy_set_header Connection "upgrade";
         }