Document per-subject evaluation telemetry opt-out

[leoromanovsky]

Motivation

Applications need to control which subjects contribute feature flag evaluation telemetry without changing flag results or experiment exposures.

Changes and Decisions

Add one concept page for the shared behavior, with configuration and evaluation examples in the browser, mobile, and server SDK guides. Document explicit activation, the Boolean context attribute, server environment configuration, and the data this control does not suppress.

The examples follow the SDK implementation branches. Unity and React Native are not included.

Merge readiness

• Ready for merge
• Confirm released minimum versions before publication and replace the upcoming-support notice.

SDK work: browser, iOS, Swift provider, Android, Dart/Flutter, Go, Java, Node.js, Python, Ruby, PHP, .NET.

AI assistance

AI-assisted drafting and API/source comparison.

[github-actions]

Preview links (active after the build_preview check completes)

New or renamed files

• https://docs-staging.datadoghq.com/leo/evaluation-telemetry-opt-out-docs/feature_flags/concepts/evaluation_telemetry_opt_out

Modified Files

• https://docs-staging.datadoghq.com/leo/evaluation-telemetry-opt-out-docs/feature_flags/client/android
• https://docs-staging.datadoghq.com/leo/evaluation-telemetry-opt-out-docs/feature_flags/client/flutter
• https://docs-staging.datadoghq.com/leo/evaluation-telemetry-opt-out-docs/feature_flags/client/ios
• https://docs-staging.datadoghq.com/leo/evaluation-telemetry-opt-out-docs/feature_flags/client/javascript
• https://docs-staging.datadoghq.com/leo/evaluation-telemetry-opt-out-docs/feature_flags/concepts/
• https://docs-staging.datadoghq.com/leo/evaluation-telemetry-opt-out-docs/feature_flags/server/dotnet
• https://docs-staging.datadoghq.com/leo/evaluation-telemetry-opt-out-docs/feature_flags/server/go
• https://docs-staging.datadoghq.com/leo/evaluation-telemetry-opt-out-docs/feature_flags/server/java
• https://docs-staging.datadoghq.com/leo/evaluation-telemetry-opt-out-docs/feature_flags/server/nodejs
• https://docs-staging.datadoghq.com/leo/evaluation-telemetry-opt-out-docs/feature_flags/server/php
• https://docs-staging.datadoghq.com/leo/evaluation-telemetry-opt-out-docs/feature_flags/server/python
• https://docs-staging.datadoghq.com/leo/evaluation-telemetry-opt-out-docs/feature_flags/server/ruby