Fix: Remove Firebase integration in order to generate new project from the script

[lydiasama]

Issue

When generateing the project from the script, it requires the google-services.json file which we saved in the Github Secrets. To support general users outside Nimble, we need to remove it to make the script can be built successfully without the Firebase integration. Besides, Codemagic supports distributing the app to Firebase App Distribution without integrating the Firebase to the project.

Expected

The generate new project script can run successfully.