Switch Android CI Pipeline to `ubuntu-latest`

[Saad Najmi]

Fallout from #1535

We use the VM image macOS-11 to run the "Android PR" ADO job in our pipeline. As was pointed out, ubuntu-latest is much much faster, so we should switch the job to use that. When I did that, the check hung. I assume this is because we're using a custom bash script. Related, we could probably also switch our check to just be a grade build invocation, similar to what react-native-test-app does in their CI.

[Ayush Singh]

The issue is that the Android Emulator is currently available only for hosted macOS agents.

[Saad Najmi]

Thanks for the update! Closing