Icu 16546 upgrade ember for admin UI (#2793)

* v4.12.2...v5.12.0

* chore: 🤖 yarn.lock changes

* chore: 🤖 ember init blueprint changes

* chore: 🤖 yarn.lock file changes

* style: 💄 run linter and formatter

✅ Closes: https://hashicorp.atlassian.net/browse/ICU-16546

ui/admin/config/ember-cli-update.json

@@ -3,13 +3,17 @@
   "packages": [
     {
       "name": "ember-cli",
-      "version": "4.12.2",
+      "version": "5.12.0",
       "blueprints": [
         {
           "name": "app",
           "outputRepo": "https://github.com/ember-cli/ember-new-output",
           "codemodsSource": "ember-app-codemods-manifest@1",
-          "isBaseBlueprint": true
+          "isBaseBlueprint": true,
+          "options": [
+            "--no-welcome",
+            "--yarn"
+          ]
         }
       ]
     }