test(integration): prevent auto-relaunch on Android

[jpnurmi]

Fixes the behavior described in #4750 (comment).

Problem

Page.OnAppearing was originally chosen for triggering test crashes because it seemed like a good place for doing it as soon as the app is visible and fully up and running. However, it turns out to be a bit too early in the sense that it causes Android to try re-launch the process. Each restarted process re-triggers the test crash, which results in intermittent extra envelopes causing test assertion failures.

Solution

Delaying the test crash until VisualElement.Loaded prevents the undesired auto-relaunch behavior on Android.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.80%. Comparing base (c8dd656) to head (398d340).
⚠️ Report is 7 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4833   +/-   ##
=======================================
  Coverage   73.80%   73.80%           
=======================================
  Files         483      483           
  Lines       17551    17551           
  Branches     3461     3461           
=======================================
  Hits        12954    12954           
  Misses       3745     3745           
  Partials      852      852           

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