Clobber checkout directory by default. This is to prevent issues with git tags not being cleaned. Change-Id: I144e781dd5bec2a215b9717b7ca648640411fd95 Bug: https://github.com/flutter/flutter/issues/62146 Reviewed-on: https://flutter-review.googlesource.com/c/recipes/+/4721 Reviewed-by: Nurhan Turgut <nurhan@google.com> Commit-Queue: Godofredo Contreras <godofredoc@google.com>