UserDefaults misbehavior monitoring

[dus7]

Task/Issue URL: https://app.asana.com/0/1206226850447395/1208659072736427/f
Tech Design URL: https://app.asana.com/0/481882893211075/1208618515043198/f
CC:

Description:

Attempt to validate a hypothesis about unreliable/inaccessible UserDefaults data during app launch.

Steps to test this PR:

Statistics loader

1. Launch the app
2. Stop and put a breakpoint in StatisticsLoader.swift:50
3. Run the app again. On breakpoint run a debugger command: expr statisticsStore.atb = nil
4. Continue execution.
5. Verify proper pixel is fired.
6. On assertion go to StatisticsLoader.load() frame in the stack and run: expr atbPresenceFileMarker?.unmark() or remove the app. This will prevent assertion for next scenario.

Ad attribution reporter

1. Change AdAttributionPixelReporter.isAdAttributionReportingEnabled to true
2. Put a breakpoint in AdAttributionPixelReporter.swift:60
3. Run the app. On breakpoint run a debugger command: expr attributionReportSuccessfulFileMarker?.mark()
4. Continue execution
5. Verify proper pixel is fired.
6. On assertion go to AdAttributionPixelReporter.reportAttributionIfNeeded() frame in the stack and run: expr attributionReportSuccessfulFileMarker?.unmark() or remove the app.

Definition of Done (Internal Only):

• Does this PR satisfy our Definition of Done?

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Internal references:

Software Engineering Expectations
Technical Design Template