Keep the intermediate APK signed the same way before going to the play store (#14484)
Keep the intermediate APK signed the same way before going to the play store (#14484)

* Keep the intermediate APK signed the same way before going to the play store

* Don't run on PRs

flutter/flutter,Hixie/flutter,tvolkert/flutter,Hixie/flutter,tvolkert/flutter,Hixie/flutter,flutter/flutter,tvolkert/flutter,cbracken/flutter,flutter/flutter,Hixie/flutter,tvolkert/flutter,cbracken/flutter,flutter/flutter,flutter/flutter,Hixie/flutter,flutter/flutter,cbracken/flutter,tvolkert/flutter,tvolkert/flutter,flutter/flutter,cbracken/flutter,cbracken/flutter,Hixie/flutter,flutter/flutter,cbracken/flutter,cbracken/flutter,Hixie/flutter,tvolkert/flutter,Hixie/flutter,tvolkert/flutter,cbracken/flutter,tvolkert/flutter,flutter/flutter,cbracken/flutter,flutter/flutter,Hixie/flutter,tvolkert/flutter,Hixie/flutter,cbracken/flutter