Explicitly annotate system APIs in SatelliteManager with @SystemApi

This change explicitly mark system APIs in SatelliteManger with
annotation @SystemApi to avoid accidentally expose unnecessary APIs when
exposing SatelliteManager class as public API in upcoming change.

SatelliteManger is @SystemApi at present. All public fields and methods
inside SatelliteManger are defacto system APIs (see system-current.txt).
So this change is no-op on the API surface

Bug: 357638490
Test: atest FrameworksTelephonyTests
Flag: EXEMPT javadoc change only
Change-Id: I9483f800ca22c8eb32d943a90a3dbc540badfc16