build: remove unused reactifex packages

Remove reactifex and @edx/reactifex packages from devDependencies as they are no longer
needed. Translation extraction functionality has been verified to work
correctly without these dependencies.

Co-Authored-By: Claude <noreply@anthropic.com>

Author: feanil

package-lock.json

@@ -63,7 +63,6 @@
   },
   "devDependencies": {
     "@edx/browserslist-config": "^1.1.0",
-    "@edx/reactifex": "^1.0.3",
     "@openedx/frontend-build": "^14.3.3",
     "@testing-library/dom": "^9.3.4",
     "@testing-library/jest-dom": "^5.17.0",
@@ -77,7 +76,6 @@
     "glob": "7.1.6",
     "jest": "^29.7.0",
     "jest-environment-jsdom": "^29.7.0",
-    "react-test-renderer": "^17.0.2",
-    "reactifex": "1.1.1"
+    "react-test-renderer": "^17.0.2"
   }
 }