Revert of production env enforcement (#2341)

* Revert d8dd446

Undoing the commit that forces the production environment. The code has it as default when not defined, this is sufficient, but it should respect the user settings!

lib/tasks/webpacker/compile.rake

@@ -26,7 +26,7 @@ end
 namespace :webpacker do
   desc "Compile JavaScript packs using webpack for production with digests"
   task compile: ["webpacker:verify_install", :environment] do
-    Webpacker.with_node_env("production") do
+    Webpacker.with_node_env(ENV.fetch("NODE_ENV", "production")) do
       ensure_log_goes_to_stdout do
         if Webpacker.compile
           # Successful compilation!