feat: Promote performanceV2 to stable

[philipphofmann]

📜 Description

Make the performanceV2 flag stable, as it's been experimental long enough, and we didn't hear any negative feedback from customers using it.

Docs PR: getsentry/sentry-docs#11913.

💡 Motivation and Context

Customers frequently want to use the feature and it only confuses them when it's experimental.

💚 How did you test it?

It's well tested with unit tests and we didn't hear any negative feedback.

📝 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

[github-actions]

	Messages
📖	Do not forget to update Sentry-docs with your feature once the pull request gets approved.

Generated by 🚫 dangerJS against 783280a

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.898%. Comparing base (07ea386) to head (783280a).
Report is 1 commits behind head on main.

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #4564       +/-   ##
=============================================
- Coverage   90.944%   90.898%   -0.047%     
=============================================
  Files          617       616        -1     
  Lines        70599     70437      -162     
  Branches     25243     25055      -188     
=============================================
- Hits         64206     64026      -180     
- Misses        6301      6318       +17     
- Partials        92        93        +1     

see 40 files with indirect coverage changes

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[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1238.08 ms	1255.65 ms	17.57 ms
Size	22.30 KiB	747.51 KiB	725.21 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
8e4bc70	1229.18 ms	1240.86 ms	11.67 ms
e072ad1	1232.43 ms	1245.51 ms	13.08 ms
302ee8b	1194.02 ms	1223.34 ms	29.32 ms
bce565d	1330.00 ms	1363.71 ms	33.71 ms
42f4107	1224.52 ms	1244.77 ms	20.25 ms
ff09c7e	1240.94 ms	1262.66 ms	21.72 ms
07b120c	1227.48 ms	1235.14 ms	7.66 ms
51307b7	1223.08 ms	1240.76 ms	17.68 ms
25a5e8b	1249.18 ms	1268.42 ms	19.24 ms
2f8b3a8	1233.76 ms	1260.24 ms	26.48 ms

App size

Revision	Plain	With Sentry	Diff
8e4bc70	21.58 KiB	625.90 KiB	604.32 KiB
e072ad1	21.58 KiB	625.83 KiB	604.24 KiB
302ee8b	20.76 KiB	419.62 KiB	398.87 KiB
bce565d	21.58 KiB	683.63 KiB	662.05 KiB
42f4107	21.58 KiB	614.92 KiB	593.34 KiB
ff09c7e	20.76 KiB	427.76 KiB	407.00 KiB
07b120c	21.58 KiB	614.90 KiB	593.32 KiB
51307b7	22.85 KiB	407.63 KiB	384.78 KiB
25a5e8b	20.76 KiB	436.33 KiB	415.57 KiB
2f8b3a8	20.76 KiB	434.72 KiB	413.96 KiB