audioserver: do not prefetch audioserver services

ServiceManager may provide stale audioserver service handles
to the new audioserver instance when it is reinitializing.

Flag: EXEMPT bugfix
Test: for run in {1..100}; do (sleep 8; echo $run; adb shell pkill audioserver); done
Test: atest service_singleton_tests
Test: atest CtsMediaAudioTestCases
Bug: 379427790
Change-Id: Ifc237bdfecca308f8a7c5be1b82612293df8aed9