SystemServiceRegistry: Avoid WTF if WifiAware is unsupported

On devices without FEATURE_WIFI_AWARE, requesting the WifiAwareManager
service triggers a "What a Terrible Failure" (WTF) log. This pollutes
the logs on platforms where the feature is intentionally absent.

Check for the feature before retrieving the service. If unsupported,
gracefully return null, preventing the WTF log entry.

Bug: 426627753
Test: Deploy to AL device and check the logs.
Flag: EXEMPT log only update
Change-Id: I0de61aacac7a0308d58f31d2d49b0712b9aaf0c6