feat(micrometer): [Micrometer 2] Add passive meter polling

[adinauer]

PR Stack (Micrometer)

• feat(micrometer): Add Micrometer metrics integration #6084
• feat(micrometer): [Micrometer 1] Add active meters #6085
• feat(micrometer): [Micrometer 2] Add passive meter polling #6114
• feat(micrometer): [Micrometer 3] Add function timer polling #6115
• feat(micrometer): [Micrometer 4] Add Spring Boot integration #6116

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📜 Description

Add fixed-rate polling for passive Micrometer meters to SentryMeterRegistry.

The registry polls gauges, time gauges, long-task timers, and function counters every 60 seconds by default. Applications can configure the interval in milliseconds or set it to zero to disable passive polling. Function counters emit positive deltas and reset their baseline when their source value decreases.

Polling resolves the active Sentry scopes at capture time, isolates callback failures between meters, skips non-finite values, and shuts down without blocking when the registry closes.

💡 Motivation and Context

Passive meters expose values through callbacks rather than record-time operations, so they cannot use the immediate forwarding added in the previous stack PR. A single registry-owned polling worker captures those values while continuing to use Sentry's existing metrics batching and transport.

FunctionTimer is intentionally deferred to the next PR because its cumulative count and total-time semantics need separate review.

💚 How did you test it?

./gradlew spotlessApply apiDump
./gradlew :sentry-micrometer:check

Tests cover each passive meter mapping, polling intervals, disabled polling, function-counter baselines and resets, callback isolation, dynamic scope resolution, meter removal, and shutdown.

📝 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

Add separately reviewed FunctionTimer polling semantics in the next stack PR.

#skip-changelog

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

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SDK Size	io.sentry.tests.size	8.56.0 (1)	release

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