feat(samples): Enable Sentry Logs in the Android sample app (#5766)

The Android sample already emits structured logs via Sentry.logger() in
MainActivity.onCreate, but they were silently dropped because the Logs
feature is disabled by default. Enable it through the manifest so the
sample demonstrates the logging feature out of the box.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>