chore: Use AGP's managed devices for instrumentation tests

[DSteve595]

This change brings in AGP's Managed Devices, setting up a Pixel 5 on API 29 (matching the device declared in the existing GitHub workflow). It also updates the GitHub workflow to run tests on that emulator, removing the dependency on reactivecircus/android-emulator-runner.
The aim is to hopefully have more reproducibility between tests run locally versus on CI. Not sure yet whether this fixes the current flaky test issue.

[DSteve595]

Execution failed for task ':app:pixel5api29Setup'.
91 actionable tasks: 91 executed
> A failure occurred while executing com.android.build.gradle.internal.tasks.ManagedDeviceSetupTask$ManagedDeviceSetupRunnable
   > Gradle was not able to complete device setup for: dev29_google_x86_Pixel_5
     This could be due to having insufficient resources to provision the number of
     devices requested. Try running the test again and request fewer devices or
     fewer shards.

I also get this locally the first run, then it resolves itself. I wonder if a newer AGP would help..

[arriolac]

You can also look at the Sunflower config (currently disabled) to see what flags you can pass in (perhaps one of those can do the trick). See: https://github.com/android/sunflower/blob/main/.github/workflows/android.yml#L66

[DSteve595]

I'm betting -Pandroid.experimental.testOptions.managedDevices.setupTimeoutMinutes will help. Trying it out.

[DSteve595]

Aww.

[DSteve595]

Turns out setupTimeoutMinutes is a lie, it's actually in seconds! Fixed in AGP here, not sure if it's made it into a release yet.

[DSteve595]

And the property seems to not be implemented in AGP 7.2, only 7.3 Need #224.