Revert "DEV: Support for running theme test with Ember CLI (second attempt)" (#15559)

This reverts commit 2c7906999a.

The changes break some things in local development (putting JS files
into minified files, not allowing debugger, and others)

config/application.rb

@@ -176,18 +176,13 @@ module Discourse
       confirm-new-email/bootstrap.js
       onpopstate-handler.js
       embed-application.js
-      discourse/tests/active-plugins.js
+      discourse/tests/theme_qunit_ember_jquery.js
+      discourse/tests/theme_qunit_vendor.js
+      discourse/tests/theme_qunit_tests_vendor.js
+      discourse/tests/theme_qunit_helper.js
       discourse/tests/test_starter.js
     }
 
-    if ENV['EMBER_CLI_PROD_ASSETS'] != "1"
-      config.assets.precompile += %w{
-        discourse/tests/test-support-rails.js
-        discourse/tests/test-helpers-rails.js
-        vendor-theme-tests.js
-      }
-    end
-
     # Precompile all available locales
     unless GlobalSetting.try(:omit_base_locales)
       Dir.glob("#{config.root}/app/assets/javascripts/locales/*.js.erb").each do |file|
@@ -375,7 +370,7 @@ module Discourse
             %w{qunit.js
               qunit.css
               test_helper.css
-              discourse/tests/test-boot-rails.js
+              discourse/tests/test_helper.js
               wizard/test/test_helper.js
             }.include?(logical_path) ||
             logical_path =~ /\/node_modules/ ||