fix: Deadline timeout crash in SentryTracer

[philipphofmann]

📜 Description

Replace the NSTimer with dispatch async, which we already use for the idle timeout and haven't had issues for a long time. Dispatch async also has the advantage that it can be called from any thread.

💡 Motivation and Context

Fixes GH-3320

💚 How did you test it?

Unit tests and simulator.l

📝 Checklist

You have to check all boxes before merging:

• 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.

🔮 Next steps

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.278%. Comparing base (90afe02) to head (b558684).
Report is 2 commits behind head on main.

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #4911       +/-   ##
=============================================
- Coverage   92.374%   92.278%   -0.097%     
=============================================
  Files          659       659               
  Lines        77547     77483       -64     
  Branches     28084     27267      -817     
=============================================
- Hits         71634     71500      -134     
- Misses        5817      5889       +72     
+ Partials        96        94        -2     

Files with missing lines	Coverage Δ
Sources/Sentry/SentryTracer.m	97.520% <100.000%> (-0.509%)	⬇️
...urces/Sentry/SentryUIEventTrackerTransactionMode.m	100.000% <100.000%> (ø)
...SentryProfilerTests/SentryProfileTestFixture.swift	99.704% <ø> (-0.001%)	⬇️
...iewController/SentryTimeToDisplayTrackerTest.swift	100.000% <100.000%> (ø)
...egrations/UIEvents/SentryUIEventTrackerTests.swift	99.600% <100.000%> (ø)
...ts/SentryTests/Transaction/SentryTracerTests.swift	99.393% <100.000%> (+0.778%)	⬆️

... and 28 files with indirect coverage changes

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[philprime]

LGTM, while I do not fully understand the usage of the timer (yet), I did not spot any obvious issues with the changes.

Tests are still failing, so we should wait for CI to be green.

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1239.49 ms	1259.18 ms	19.69 ms
Size	22.31 KiB	821.12 KiB	798.82 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
ea73af6	1241.69 ms	1252.96 ms	11.27 ms
9b9f2a0	1233.36 ms	1244.04 ms	10.68 ms
38b36f5	1218.48 ms	1246.61 ms	28.13 ms
443723a	1205.24 ms	1220.52 ms	15.28 ms
7cd187e	1239.02 ms	1261.42 ms	22.40 ms
ed64658	1225.06 ms	1247.73 ms	22.67 ms
0dfdaaa	1226.88 ms	1248.82 ms	21.94 ms
b35ccd0	1233.92 ms	1256.69 ms	22.78 ms
8cb9355	1225.23 ms	1231.22 ms	5.99 ms
4af7581	1214.55 ms	1237.10 ms	22.55 ms

App size

Revision	Plain	With Sentry	Diff
ea73af6	20.76 KiB	425.76 KiB	404.99 KiB
9b9f2a0	21.58 KiB	707.42 KiB	685.84 KiB
38b36f5	21.58 KiB	616.35 KiB	594.77 KiB
443723a	20.76 KiB	414.44 KiB	393.68 KiB
7cd187e	20.76 KiB	401.65 KiB	380.89 KiB
ed64658	22.30 KiB	749.84 KiB	727.54 KiB
0dfdaaa	20.76 KiB	434.56 KiB	413.79 KiB
b35ccd0	21.58 KiB	573.13 KiB	551.55 KiB
8cb9355	20.76 KiB	419.70 KiB	398.95 KiB
4af7581	22.84 KiB	401.62 KiB	378.77 KiB