MobX removal take 2 (#5381)

* mobx removal take 2

* Actually rm mobx

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Co-authored-by: Dan Abramov <dan.abramov@gmail.com>

package.json

@@ -161,9 +161,6 @@
     "lodash.set": "^4.3.2",
     "lodash.shuffle": "^4.2.0",
     "lodash.throttle": "^4.1.1",
-    "mobx": "^6.6.1",
-    "mobx-react-lite": "^3.4.0",
-    "mobx-utils": "^6.0.6",
     "nanoid": "^5.0.5",
     "normalize-url": "^8.0.0",
     "patch-package": "^6.5.1",