feat(core): [Logs and Metrics Enable Flags 9] Warn for legacy Logs configuration

[adinauer]

PR Stack (Logs and Metrics Enable Flags)

• feat(core): Remove Logs and Metrics enable flags #5939
• feat(logback): [Logs and Metrics Enable Flags 1] Add Logs opt-in #5940
• feat(log4j2): [Logs and Metrics Enable Flags 2] Add Logs opt-in #5941
• feat(jul): [Logs and Metrics Enable Flags 3] Add Logs opt-in #5942
• feat(android): [Logs and Metrics Enable Flags 4] Add Timber Logs opt-in #5943
• feat(android): [Logs and Metrics Enable Flags 5] Add Logcat Logs opt-in #5945
• feat(spring): [Logs and Metrics Enable Flags 6] Add logging Logs opt-in #5946
• feat(core): [Logs and Metrics Enable Flags 7] Remove Logs enable flag #5947
• feat(android): [Logs and Metrics Enable Flags 8] Warn for legacy Logs metadata #5949
• feat(core): [Logs and Metrics Enable Flags 9] Warn for legacy Logs configuration #5950
• feat(spring): [Logs and Metrics Enable Flags 10] Warn for legacy Logs property #5951
• perf(core): [Logs and Metrics Enable Flags 11] Avoid unused Logs worker thread #5952
• feat(core): [Logs and Metrics Enable Flags 12] Remove Metrics enable flag #5953
• feat(android): [Logs and Metrics Enable Flags 13] Warn for legacy Metrics metadata #5954
• feat(core): [Logs and Metrics Enable Flags 14] Warn for legacy Metrics configuration #5955
• feat(spring): [Logs and Metrics Enable Flags 15] Warn for legacy Metrics property #5956
• perf(core): [Logs and Metrics Enable Flags 16] Avoid unused Metrics worker thread #5957
• fix(jul): [Logs and Metrics Enable Flags 17] Preserve null-message records #5960
• docs: [Logs and Metrics Enable Flags 18] Update options guidance #5961

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📜 Description

Keeps parsing the nullable legacy logs.enabled external option and emits a tailored migration warning from SentryOptions.merge for explicit true and false values.

The legacy value no longer changes SDK behavior. Manual Sentry.logger() capture remains active for either value, while absent configuration emits no warning.

💡 Motivation and Context

The aggregate Logs enable flag was removed earlier in this stack. Existing sentry.properties, environment-variable, and system-property configurations need a clear migration diagnostic rather than being silently ignored.

💚 How did you test it?

• ./gradlew :sentry:test
• ./gradlew spotlessApply apiDump
• Added external parsing tests for absent, true, and false values
• Added merge tests for tailored warnings and unchanged manual Logs capture

📝 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

Add the equivalent migration warning for legacy Spring Boot Logs configuration.

#skip-changelog

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

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

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[sentry]

📲 Install Builds

Android

🔗 App Name	App ID	Version	Configuration
SDK Size	io.sentry.tests.size	8.52.0 (1)	release

⚙️ sentry-android Build Distribution Settings

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Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	317.73 ms	376.65 ms	58.92 ms
Size	0 B	0 B	0 B

Previous results on branch: feat/warn-legacy-logs-external

Startup times

Revision	Plain	With Sentry	Diff
623c4e5	312.67 ms	343.90 ms	31.23 ms

App size

Revision	Plain	With Sentry	Diff
623c4e5	0 B	0 B	0 B