Swap crash reporting with unified analytics

[eliasyishak]

Fixes:

• Use package:unified_analytics to decide if we should send a crash report #147260

Pre-launch Checklist

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• I listed at least one issue that this PR fixes in the description above.
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• I added new tests to check the change I am making, or this PR is test-exempt.
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[christopherfujino]

What about instead we just use our own implementation of this class, such as:

class FakeAnalytics extends Fake implements Analytics {
  const FakeAnalytics({this.okToSend = true});
  
  @override
  bool okToSend;
  
  @override
  void suppressTelemetry() => okToSend = false;
}

[andrewkolos]

I haven't done a deep dive on getInitializedFakeAnalyticsInstance, but I am inclined to agree with this suggestion. Speaking generally, I think it's good for a test to fake as little as needed so that it's more clear as to what that test depends upon.