Fix audio HAL restart sequence to improve uptime

Do not use 'restart vendor.audio-hal' directly when serving the
framework request for HAL restart via 'sys.audio.restart.hal'
property.  This is to avoid triggering 'onrestart' event the .rc
file of the audio HAL service. Instead use 'stop / start'
sequence.

Do not use the 'sys.audio.restart.hal' property for handling
audioserver restart to avoid race conditions.

Bug: 151795571
Bug: 159966243
Test: 1) repro steps from b/151795571
      2) adb shell stop, verify that audio HAL is running
         and has been restarted (has different PID from prior
         to adb shell stop)
Change-Id: I5d87f4bba93153a84fe35c7a740e05960dcb6997
Merged-In: I5d87f4bba93153a84fe35c7a740e05960dcb6997