Remove unused Jest setup

Author: paulrobertlloyd

jest.setup.js

@@ -27,16 +27,12 @@
     "jest": "^30.1.1",
     "jest-environment-jsdom": "^30.1.1",
     "jest-fetch-mock": "^3.0.3",
-    "mutationobserver-shim": "^0.3.7",
     "officecrypto-tool": "^0.0.19",
     "playwright-core": "^1.55.0",
     "prettier": "^3.6.2"
   },
   "jest": {
     "collectCoverage": true,
-    "setupFilesAfterEnv": [
-      "<rootDir>/jest.setup.js"
-    ],
     "testPathIgnorePatterns": [
       "app/assets/builds/",
       "node_modules/",