DEV: Update ember-cli to 5.6.0 (#25886)

app/assets/javascripts/discourse-common/config/ember-cli-update.json

@@ -1,20 +0,0 @@
-{
-  "schemaVersion": "1.0.0",
-  "packages": [
-    {
-      "name": "ember-cli",
-      "version": "5.0.0",
-      "blueprints": [
-        {
-          "name": "addon",
-          "outputRepo": "https://github.com/ember-cli/ember-addon-output",
-          "codemodsSource": "ember-addon-codemods-manifest@1",
-          "isBaseBlueprint": true,
-          "options": [
-            "--no-welcome"
-          ]
-        }
-      ]
-    }
-  ]
-}

app/assets/javascripts/discourse-common/package.json

@@ -14,7 +14,7 @@
     "start": "ember serve"
   },
   "dependencies": {
-    "@ember/string": "^3.1.1",
+    "@babel/core": "^7.23.7",
     "@uppy/aws-s3": "3.0.6",
     "@uppy/aws-s3-multipart": "3.1.3",
     "@uppy/core": "3.0.4",
@@ -37,7 +37,7 @@
     "@types/qunit": "^2.19.10",
     "@types/rsvp": "^4.0.9",
     "broccoli-asset-rev": "^3.0.0",
-    "ember-cli": "~5.0.0",
+    "ember-cli": "~5.6.0",
     "ember-cli-inject-live-reload": "^2.1.0",
     "ember-cli-sri": "^2.1.1",
     "ember-cli-terser": "^4.0.2",
@@ -49,7 +49,7 @@
     "webpack": "^5.90.3"
   },
   "engines": {
-    "node": "16.* || >= 18",
+    "node": ">= 18",
     "npm": "please-use-yarn",
     "yarn": ">= 1.21.1"
   },