fix: EXC_BAD_ACCESS in SentryTracer

[philipphofmann]

📜 Description

Fix EXC_BAD_ACCESS in SentryTracer by using a weak reference when dispatching the idle timeout to avoid accessing a garbage pointer.

💡 Motivation and Context

Fixes GH-2696

💚 How did you test it?

Unit test.

📝 Checklist

• I reviewed the submitted code.
• 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.
• 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.

🔮 Next steps

[codecov]

Codecov Report

Merging #2697 (11dd192) into main (e9782e1) will decrease coverage by 0.06%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2697      +/-   ##
==========================================
- Coverage   80.65%   80.60%   -0.06%     
==========================================
  Files         247      247              
  Lines       22898    22934      +36     
  Branches    10136    10155      +19     
==========================================
+ Hits        18468    18485      +17     
- Misses       3968     3988      +20     
+ Partials      462      461       -1     

Impacted Files	Coverage Δ
Sources/Sentry/SentryTracer.m	97.29% <100.00%> (-0.56%)	⬇️
Sources/Sentry/SentryProfilingLogging.mm	0.00% <0.00%> (-51.86%)	⬇️
Sources/Sentry/include/SentryMachLogging.hpp	62.50% <0.00%> (-12.50%)	⬇️
Sources/Sentry/include/SentryProfilingLogging.hpp	45.45% <0.00%> (-9.10%)	⬇️
Sources/Sentry/SentryMachLogging.cpp	2.51% <0.00%> (-1.01%)	⬇️
Sources/Sentry/SentryANRTracker.m	100.00% <0.00%> (ø)
Sources/Sentry/SentryCrashIntegration.m	98.66% <0.00%> (+0.03%)	⬆️
Sources/Sentry/SentryNetworkTracker.m	95.34% <0.00%> (+0.06%)	⬆️
Sources/Sentry/SentryUser.m	95.74% <0.00%> (+2.97%)	⬆️
... and 1 more

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