Update sampleRate in DSC

[adinauer]

📜 Description

Whenever tracesSampleRate or tracesSampler callback or manually setting a sampling decision happen, we want to update the sampleRate in DSC to have it reflect what was actually used.

💡 Motivation and Context

Closes #4116

💚 How did you test it?

📝 Checklist

• 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 715eef8

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	498.06 ms	609.19 ms	111.13 ms
Size	1.58 MiB	2.21 MiB	641.10 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
c2c78de	415.28 ms	505.08 ms	89.80 ms

App size

Revision	Plain	With Sentry	Diff
c2c78de	1.58 MiB	2.21 MiB	640.27 KiB

Previous results on branch: feat/update-dsc-sample-rate

Startup times

Revision	Plain	With Sentry	Diff
7adf69b	492.39 ms	503.90 ms	11.51 ms

App size

Revision	Plain	With Sentry	Diff
7adf69b	1.58 MiB	2.21 MiB	640.93 KiB

[lcian]

LGTM

[lbloder]

LGTM 👍