fix(scopes): Walk parent chain iteratively in isAncestorOf

[hocaron]

📜 Description

Scopes.isAncestorOf recursed once per parent link. It now walks the parentScopes chain with a loop, so a long chain can't throw StackOverflowError. Behaviour is otherwise unchanged.

💡 Motivation and Context

Split out from #6248, as mentioned there. This PR does not fix the leak itself, only the stack overflow a long chain can cause.

Long Scopes chains happen in practice: a task that re-schedules itself through SentryScheduleHook gets a new fork whose parent is the previous run's fork (see #6248, similar to #5051). We saw chains of ~38k links after ~13 days in production.

Since #6004, Sentry.getCurrentScopes() calls root.isAncestorOf(scopes) in globalHubMode, so the recursion can run on a hot path. The OTel SentryContextWrapper also calls isAncestorOf.

• Refs Memory leak: SentryScheduleHook builds an unbounded Scopes chain for self-rescheduling tasks (reactor-netty pool eviction) #6248
• Linear: JAVA-773

💚 How did you test it?

Added ScopesTest › isAncestorOf does not overflow the stack on a deep chain: builds 20,000 chained forkedCurrentScope forks and calls root.isAncestorOf(deepest) on a thread with a 256 KB stack.

• On main: fails with expected:<true> but was:<java.lang.StackOverflowError>
• With this change: passes

./gradlew :sentry:test :sentry:apiCheck :sentry:spotlessCheck passes locally (JDK 17).

📝 Checklist

• I added GH Issue ID & Linear ID
• I added tests to verify the changes.
• No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled.
• I updated the docs if needed.
• I updated the wizard if needed.
• Review from the native team if needed.
• No breaking change or entry added to the changelog.
• No breaking change for hybrid SDKs or communicated to hybrid SDKs.
• Public API changes reviewed by another Mobile SDK team member or implemented according to the develop docs spec.

🔮 Next steps

The fix that stops the chain from growing in the first place is proposed in #6248.