Fix flaky ui-testing GitHub Actions workflow

[mataku]

Context

In #342, I made testing GitHub Actions workflow work, which hadn't been working for some time. In the process of code review, I heard ui-testing workflow is unstable.

On my forked repo: https://github.com/mataku/Showkase, I tried to investigate with androidTest result reports but no particularly useful logs were displayed (like: #341 (comment))

I thought Android emulator itself may be unstable. After updating Android emulator, it seems to be stable. Tried with many retries: https://github.com/mataku/Showkase/actions/runs/5991426769

Changes

• Update emulator build version
• Upload AndroidTest report results regardless of whether the test was successful or unsuccessful to investigate easily
• Regenerate screenshots in sample/screenshots/debug

[vinaygaba]

@mataku Thank you so much for investigating and helping with making the CI more reliable 🙏🏻

Do you know where the screenshot diffs on this PR are stemming from?

[mataku]

@vinaygaba
I don't know the details, but I replaced them after updating emulator because the test failed as it was.

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Anyway, as you can see, this change is not enough because workflow results are still flaky. So I will look at it again when I have the time.