A few changes in this PR (could have been split up, but that would take
an extra 4 hours - 2 days in CI time):
- Removed the old `flutter_driver_android_test` shards and references
- Override `AndroidManifest.xml` per backend, forcing that backend to be
used (no fallbacks) or it fails
- Bumps the Android emulator to 35 due to the use of magic strings, I
think
The check for the Impeller backend actually being used is the honor
system right now, as a bug in `flutter drive`
(https://github.com/flutter/flutter/issues/162087) prevents me from
seeing error output, meaning that it's impossible to be sure a
particular Impeller backend is used (or understand why a crash happens),
so I guess I'll work on that next.
Due to https://github.com/flutter/flutter/issues/162088, we were
accidentally running our Vulkan tests as OpenGLES 🤦🏼 .
Towards https://github.com/flutter/flutter/issues/161261 (before I add
more tests).
This is a 1:1 move, with massaging of
`run_flutter_driver_android_tests.dart` to be more automated as tests
are added.
/cc @reidbaker
