impr: Speed up SentryNetworkTracker

[philipphofmann]

📜 Description

Speed up SentryNetworkTracker for multiple HTTP requests in parallel by removing unnecessary locks.

@brustolin, you added these locks in the past. Can you recall if there was a good reason for that, except a race condition? I just want to double-check, that we don't break anything.

💡 Motivation and Context

This surfaced while investigating a potential slow down for a specific UIViewController when enabling the Sentry Cocoa SDK.

💚 How did you test it?

Running unit performance tests locally. Sadly, they don't work in CI, so adding them to the repository adds no value.

📝 Checklist

You have to check all boxes before merging:

• 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]

🚨 Detected changes in high risk code 🚨

High-risk code can easily blow up and is hard to test. We had severe bugs in the past. Be extra careful when changing these files, and have an extra careful look at these:

• Sources/Sentry/SentryNetworkTracker.m

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.512%. Comparing base (2233968) to head (976c1d0).
Report is 1 commits behind head on main.

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #4366       +/-   ##
=============================================
+ Coverage   91.502%   91.512%   +0.010%     
=============================================
  Files          627       627               
  Lines        50624     50618        -6     
  Branches     18295     18302        +7     
=============================================
  Hits         46322     46322               
+ Misses        4209      4204        -5     
+ Partials        93        92        -1     

Files with missing lines	Coverage Δ
Sources/Sentry/SentryNetworkTracker.m	96.742% <100.000%> (-0.073%)	⬇️

... and 4 files with indirect coverage changes

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[github-actions]

🚨 Detected changes in high risk code 🚨

High-risk code can easily blow up and is hard to test. We had severe bugs in the past. Be extra careful when changing these files, and have an extra careful look at these:

• Sources/Sentry/SentryNetworkTracker.m