fix(sentry-okhttp): Skip synthetic 504 for FORCE_CACHE cache misses

[markushi]

📜 Description

OkHttp's CacheInterceptor synthesizes a 504 "Unsatisfiable Request" response when a request with only-if-cached (e.g. CacheControl.FORCE_CACHE) misses the cache. This is not a real server error, so we should not capture it as a failed request event.

This PR adds a check in SentryOkHttpInterceptor to skip reporting when the response is a 504 and the request has onlyIfCached set.

💡 Motivation and Context

• resolves: sentry-okhttp reports spurious 504 errors for CacheControl.FORCE_CACHE requests #5276

💚 How did you test it?

• Added unit test for synthetic 504 from FORCE_CACHE cache miss (verifies no event is captured)
• Added unit test for real 504 without onlyIfCached (verifies event is still captured)
• Ran full SentryOkHttpInterceptorTest suite — all tests pass

📝 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

[github-actions]

Semver Impact of This PR

🟢 Patch (bug fixes)

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Bug Fixes 🐛

• (sentry-okhttp) Skip synthetic 504 for FORCE_CACHE cache misses by markushi in #5299

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[sentry]

📲 Install Builds

Android

🔗 App Name	App ID	Version	Configuration
SDK Size	io.sentry.tests.size	8.39.1 (1)	release

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