Improve the reliability of the Android GitHub action workflow

[desrosj]

What problem does this address?

The React Native E2E Tests (Android) GitHub Action workflows is highly unreliable and frequently fails with a few common error messages, which include:

• Timeout waiting for emulator to boot. (see here).
• The template is not valid. .github/workflows/rnmobile-android-runner.yml (Line: 46, Col: 24): hashFiles('**/*.gradle') couldn't finish within 120 seconds. (see here).

The workflow is commonly not restarted, and often fails on successive re-runs. This results in inaccurate status reporting for commits, and it seems most folks don't bother to restart it anymore.

What is your proposed solution?

There are several improvements I'd like to try out to hopefully increase the rate of success for this workflow.

• According to the README for the ReactiveCircus/android-emulator-runner third-party action currently being used, tehre are ways to significantly improve the startup time, including a recommendation to not cache Gradle manually and instead use gradel/gradle-build-action, and add caching of the AVD.
• Generate snapshots in a separate step than test running.

Additionally, it seems that a specific emulator-build (7425822) is pinned to the action, seemingly to help prevent timeout issues. However, new builds have been published since, and it's possible they don't suffer from these issues.

[desrosj]

I'm going to close this out. It's been a few years now and the workflow seems to have become more reliable.

If this turns out to still be a problem, a new issue can be opened.