Close backpressure monitor on SDK shutdown

[adinauer]

📜 Description

Close backpressure monitor on SDK shutdown

💡 Motivation and Context

Due to the backpressure monitor rescheduling a task at 10s intervals, there's a very high chance of a task currently being scheduled at any time that takes longer than the shutdownTimeoutMillis (defaulting to 2s) before it'll run. When the SDK shuts down, it'll first ask the ScheduledExecutorService to shutdown, not accepting any more new scheduled jobs but giving already scheduled jobs a chance to run. This means the SDK shutdown will almost always be delayed by the backpressure monitors scheduled job before it forcefully shuts down ScheduledExecutorService after waiting shutdownTimeoutMillis

💚 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]

	Fails
🚫	Please consider adding a changelog entry for the next release.

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

Instructions and example for changelog

Please add an entry to CHANGELOG.md to the "Unreleased" section. Make sure the entry includes this PR's number.

Example:

## Unreleased

- Close backpressure monitor on SDK shutdown ([#3998](https://github.com/getsentry/sentry-java/pull/3998))

If none of the above apply, you can opt out of this check by adding #skip-changelog to the PR description.

Generated by 🚫 dangerJS against 18f8d71

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	419.96 ms	439.00 ms	19.04 ms
Size	1.65 MiB	2.31 MiB	676.92 KiB

Baseline results on branch: feat/otel-span-strongref

Startup times

Revision	Plain	With Sentry	Diff
33c9aac	393.47 ms	407.26 ms	13.79 ms
b387fed	417.02 ms	519.06 ms	102.04 ms
c658b5a	410.55 ms	461.18 ms	50.63 ms

App size

Revision	Plain	With Sentry	Diff
33c9aac	1.65 MiB	2.31 MiB	677.05 KiB
b387fed	1.65 MiB	2.31 MiB	677.07 KiB
c658b5a	1.65 MiB	2.31 MiB	677.05 KiB

Previous results on branch: feat/close-backpressure-monitor

Startup times

Revision	Plain	With Sentry	Diff
984abce	391.53 ms	473.72 ms	82.19 ms
c8a8f47	497.30 ms	571.80 ms	74.50 ms

App size

Revision	Plain	With Sentry	Diff
984abce	1.65 MiB	2.31 MiB	676.92 KiB
c8a8f47	1.65 MiB	2.31 MiB	676.91 KiB

[lbloder]

LGTM 👍