[NativeAOT] Stabilize DoNotLeakWeakReferences by runtime-specific surfaced-object tolerance

[Copilot]

DoNotLeakWeakReferences is intermittently failing under NativeAOT because Runtime.GetSurfacedObjects() can include higher transient process-global noise than the previous assertion window allowed. The test should continue detecting real leaks without failing on runtime-specific baseline drift.

• Test assertion robustness

  • Keep existing tolerance for non-NativeAOT runs (±10).
  • Use a wider tolerance only when Microsoft.Android.Runtime.RuntimeFeature.IsNativeAotRuntime is enabled (±30).
  • Apply this tolerance to both in-thread (#2) and post-GC (#3) surfaced-object count assertions.

• Behavioral intent

  • Preserve strict leak detection semantics across runtimes.
  • Reduce false negatives caused by NativeAOT-specific transient surfaced-object churn.

const int defaultTolerance = 10;
const int nativeAotTolerance = 30;
int tolerance = AppContext.TryGetSwitch (
	"Microsoft.Android.Runtime.RuntimeFeature.IsNativeAotRuntime",
	out bool isNativeAotRuntime) && isNativeAotRuntime
	? nativeAotTolerance
	: defaultTolerance;