Remove `android.enableJetifier` (#44876)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/44876

We probably don't need Jetifier anymore at this point.
Also see: https://github.com/react-native-community/template/pull/9

Changelog:
[Internal] [Changed] - Remove `android.enableJetifier`

Reviewed By: rshest

Differential Revision: D58416487

fbshipit-source-id: f60c58aaf17b90c610959589fcd46026979c749a