Migrate Integration Quality Scale from docs to manifest: internal (#30551)

homeassistant/components/python_script/manifest.json

@@ -4,5 +4,6 @@
   "documentation": "https://www.home-assistant.io/integrations/python_script",
   "requirements": ["restrictedpython==5.0"],
   "dependencies": [],
-  "codeowners": []
+  "codeowners": [],
+  "quality_scale": "internal"
 }