hal: fix failure in running VtsHalAudioV2_0Target module

VtsHalAudioV2_0Target fails to execute completely and results in
failure of target boot up after VTS execution as system server waits
indefinitely for audioserver to come up. This is due to fd leaks while
running the test cases in the module.

Disable dolby flag on all relevant targets and close open fds in
deinit of sound monitor to resolve fd leaks. This ensures successful
execution of VTS and proper target reboot after execution of VTS.

CRs-Fixed: 2067095
Change-Id: Id4c9b680017f591dec8df385280888cc893dca8a