fix: Guard FramesTracker start and stop

[philipphofmann]

📜 Description

Profiling starts the frames tracker if it's not running, but the frames tracker again subscribes to the didBecomeActive and willResignActive notifications. To fix this, the start operation is a NoOp now if the frames tracker has already started. The same applies to stop.

💡 Motivation and Context

This came up while investigating long TTID spans for a customer.

💚 How did you test it?

Unit tests.

📝 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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.375%. Comparing base (61249fb) to head (e4c5e03).

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #4224       +/-   ##
=============================================
- Coverage   91.350%   90.375%   -0.976%     
=============================================
  Files          610       610               
  Lines        48963     48811      -152     
  Branches     17596     17330      -266     
=============================================
- Hits         44728     44113      -615     
- Misses        4142      4605      +463     
  Partials        93        93               

Files	Coverage Δ
SentryTestUtils/TestDisplayLinkWrapper.swift	95.161% <100.000%> (-0.077%)	⬇️
...tryTestUtils/TestNSNotificationCenterWrapper.swift	90.909% <100.000%> (+9.090%)	⬆️
Sources/Sentry/SentryFramesTracker.m	98.692% <100.000%> (-0.623%)	⬇️
...ance/FramesTracking/SentryFramesTrackerTests.swift	99.530% <100.000%> (+0.015%)	⬆️

... and 101 files with indirect coverage changes

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[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1223.00 ms	1230.06 ms	7.06 ms
Size	21.58 KiB	694.58 KiB	673.00 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
d10ae0c	1250.02 ms	1253.74 ms	3.72 ms
f25febb	1224.69 ms	1247.38 ms	22.68 ms
e324230	1225.84 ms	1250.40 ms	24.57 ms
d3abae0	1200.36 ms	1224.22 ms	23.87 ms
16450b8	1196.33 ms	1217.26 ms	20.93 ms
7cd187e	1229.02 ms	1233.06 ms	4.04 ms
3297d6e	1206.80 ms	1213.86 ms	7.06 ms
4af7581	1204.67 ms	1241.33 ms	36.66 ms
f1a6589	1253.67 ms	1269.06 ms	15.39 ms
7bc3c0d	1212.35 ms	1228.94 ms	16.59 ms

App size

Revision	Plain	With Sentry	Diff
d10ae0c	20.76 KiB	419.86 KiB	399.10 KiB
f25febb	21.58 KiB	414.92 KiB	393.34 KiB
e324230	22.85 KiB	408.87 KiB	386.02 KiB
d3abae0	20.76 KiB	434.92 KiB	414.16 KiB
16450b8	22.85 KiB	410.98 KiB	388.13 KiB
7cd187e	20.76 KiB	401.65 KiB	380.89 KiB
3297d6e	21.58 KiB	418.44 KiB	396.86 KiB
4af7581	22.84 KiB	401.62 KiB	378.78 KiB
f1a6589	22.85 KiB	408.87 KiB	386.02 KiB
7bc3c0d	20.76 KiB	427.35 KiB	406.59 KiB

Previous results on branch: fix/frames-tracker-start-stop

Startup times

Revision	Plain	With Sentry	Diff
a221130	1224.69 ms	1240.04 ms	15.35 ms

App size

Revision	Plain	With Sentry	Diff
a221130	21.58 KiB	694.58 KiB	672.99 KiB