Fix UncaughtExceptionHandlerIntegration Memory Leak

[lbloder]

Upon registration check if an UncaughtExceptionHandlerIntegration is already set as defaultUncaughtExceptionHandler, if so, set its defaultExceptionHandler as the default of the new UncaughtExceptionHandlerIntegration.

💡 Motivation and Context

Fixes #3266

💚 How did you test it?

📝 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

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	372.02 ms	439.62 ms	67.60 ms
Size	1.70 MiB	2.28 MiB	592.99 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
baaf637	462.32 ms	579.22 ms	116.90 ms
28c9a83	416.98 ms	479.90 ms	62.92 ms
201048a	418.62 ms	481.67 ms	63.05 ms
7ab32b6	373.62 ms	480.61 ms	106.99 ms
b172d4e	352.92 ms	446.50 ms	93.58 ms
3d8bd2b	364.76 ms	469.98 ms	105.22 ms
1e05e43	411.00 ms	467.29 ms	56.29 ms
c554ca2	383.78 ms	449.84 ms	66.06 ms
0bd723b	375.20 ms	452.41 ms	77.20 ms
99a51e2	405.11 ms	479.65 ms	74.54 ms

App size

Revision	Plain	With Sentry	Diff
baaf637	1.72 MiB	2.27 MiB	558.42 KiB
28c9a83	1.70 MiB	2.28 MiB	592.00 KiB
201048a	1.70 MiB	2.28 MiB	592.32 KiB
7ab32b6	1.70 MiB	2.27 MiB	584.63 KiB
b172d4e	1.72 MiB	2.29 MiB	578.09 KiB
3d8bd2b	1.72 MiB	2.29 MiB	577.53 KiB
1e05e43	1.70 MiB	2.28 MiB	590.89 KiB
c554ca2	1.70 MiB	2.27 MiB	582.25 KiB
0bd723b	1.72 MiB	2.29 MiB	578.09 KiB
99a51e2	1.72 MiB	2.29 MiB	576.34 KiB

[romtsn]

nice!

[adinauer]

Thanks for taking care of this!