Remove DE language from staging (#17038)

Co-authored-by: chiedo <chiedo@users.noreply.github.com>

Author: chiedo

app.json

@@ -3,7 +3,7 @@
   "env": {
     "NODE_ENV": "production",
     "NPM_CONFIG_PRODUCTION": "true",
-    "ENABLED_LANGUAGES": "en, de"
+    "ENABLED_LANGUAGES": "en"
   },
   "buildpacks": [
     { "url": "https://github.com/DataDog/heroku-buildpack-datadog.git#1.21" },