Revert "Merge branch 'mg-webpack-middleware-pass-host' into 'master'"

This reverts merge request !46753

lib/gitlab/webpack/dev_server_middleware.rb

@@ -19,7 +19,6 @@ module Gitlab
       # disable SSL check since any cert used here will likely be self-signed
       def rewrite_env(env)
         env["rack.ssl_verify_none"] = true
-        env["HTTP_HOST"] = @proxy_host
         env
       end