Restart HAL service via stop/start when audioserver is stopped

This interim solution satisfies requirements of performance
tests (audioserver stopped together with zygote) and
requirements of VTS tests (audio HAL keeps running when
zygote stops).

Bug: 155364397
Test: atest VtsHalAudioV6_0TargetTest
      atest VtsHalAudioEffectV6_0TargetTest
Change-Id: I111f0cc397024a38e146981d1e5299ce4f6bd5e2