perf(core): [SDK Overhead reduction for JVM 2] Short-circuit combined scope breadcrumbs

[adinauer]

PR Stack (SDK Overhead reduction for JVM)

• perf(core): SDK Overhead reduction for JVM #5535
• perf(core): [SDK Overhead reduction for JVM 1] Remove redundant event map copies #5536
• perf(core): [SDK Overhead reduction for JVM 2] Short-circuit combined scope breadcrumbs #5540

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📜 Description

Short-circuit CombinedScopeView.getBreadcrumbs() when only one component scope contains breadcrumbs.

The method now returns the single non-empty scope queue directly, keeps the existing merged/sorted bounded queue path when multiple scopes have breadcrumbs, and uses the configured default write scope when all queues are empty.

💡 Motivation and Context

This implements the breadcrumb portion of AR-08 from the SDK overhead reduction research. The previous code always allocated a temporary list, copied breadcrumbs from all three scopes, sorted them, allocated a bounded queue, and copied them again, even when only one scope had breadcrumbs.

Avoiding that merge path reduces per-event allocation overhead on the common single-scope breadcrumb path.

💚 How did you test it?

• ./gradlew :sentry:test --tests io.sentry.CombinedScopeViewTest
• ./gradlew spotlessApply apiDump :sentry:test --tests io.sentry.CombinedScopeViewTest

📝 Checklist

• I added GH Issue ID & Linear ID
• 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

#skip-changelog

⚠️ Merge this PR using a merge commit (not squash). Only the collection branch is squash-merged into main.

[sentry]

📲 Install Builds

Android

🔗 App Name	App ID	Version	Configuration
SDK Size	io.sentry.tests.size	8.43.2 (1)	release

⚙️ sentry-android Build Distribution Settings

[adinauer]

Closing because this PR was based on #5536. Recreated against the collection branch as #5541.