chore: init tracker gets updates synchronously before action appliers

[tanderson-ld]

Note

Reorders CompositeObserver wiring so InitializationObserver processes updates before action appliers, and adds a test covering initializer→synchronizer flow.

• FDv2 data source wiring:
  • Reorder CompositeObserver arguments to place InitializationObserver before action appliers in both initializers and synchronizers (FDv2DataSource.cs).
• Tests:
  • Add OneInitializerOneSynchronizerIsWellBehaved validating status sequence and apply calls when transitioning from initializer to synchronizer.

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