xcodebuild command generates a xcresult bundle file on each run, however, it doesn't delete the file generated from previous run and will throw an error if the exact file already exists.

In tool, we manually delete the file after each `flutter build` or `flutter run` command. However, there are some internal logic where xcodebuild retries multiple times. 

This PR deletes the xcresult bundle file at the start of each retry if it exists.

Fixes https://github.com/flutter/flutter/issues/127119