ref(core): [Callback Errors 2] Mark SDK-owned event processors

[adinauer]

PR Stack (Callback Errors)

• fix(core): Handle callback errors #6140
• fix(core): [Callback Errors 1] Report callback failures #6141
• ref(core): [Callback Errors 2] Mark SDK-owned event processors #6162
• fix(core): [Callback Errors 3] Drop failed processor data #6142
• fix(core): [Callback Errors 4] Drop failed breadcrumbs #6143
• fix(core): [Callback Errors 5] Handle tracesSampler failures #6163
• fix(core): [Callback Errors 6] Handle profilesSampler failures #6164
• fix(core): [Callback Errors 7] Handle replay sampling failures #6165

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📜 Description

Adds the internal SentryEventProcessor marker and applies it to all 25 SDK-owned event processor implementations across core, Android, Servlet, Spring, and OpenTelemetry. Customer processors continue implementing EventProcessor; BackfillingEventProcessor remains independent.

This is preparatory only: exception handling and event delivery behavior are unchanged.

💡 Motivation and Context

SDK integrations register processors through the same options and scope APIs as customers, so registration location cannot identify ownership. The marker lets #6142 distinguish SDK processors from customer processors when its failure policy is updated later, without adding a method to the customer-facing interface.

Refs #6081.

💚 How did you test it?

• ./gradlew spotlessApply apiDump
• ./gradlew :sentry:test --tests='*SentryEventProcessorTest*' apiCheck --info
• Both provenance tests passed; API checks passed.
• Audited production implementations, including Android's backfilling processor and Spring's nested request-body processors.

📝 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.
• Public API changes reviewed by another Mobile SDK team member or implemented according to the develop docs spec.

🔮 Next steps

Update #6142 to apply customer-callback failure handling only to unmarked processors. Customer subclasses of SDK processors inherit the marker; this marker identifies the SDK class hierarchy, not arbitrary overridden method ownership.

#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	8.57.0 (1)	release

⚙️ sentry-android Build Distribution Settings