add driver test command to cirrus (#1342)
add driver test command to cirrus (#1342)

This teaches Cirrus to run the new drive-examples command added in flutter/plugin_tools#29 on iOS and Android simulators.

I'm sharding the plugins tests more and requesting more powerful Linux VMs to ensure that the tests don't time out now that they're running simulators.
firebase/flutterfire,firebase/flutterfire,googleads/googleads-mobile-flutter,firebase/flutterfire,firebase/flutterfire,googleads/googleads-mobile-flutter,firebase/flutterfire,firebase/flutterfire,firebase/flutterfire,googleads/googleads-mobile-flutter,googleads/googleads-mobile-flutter,firebase/flutterfire,firebase/flutterfire,firebase/flutterfire