Policy config parser: migrate to BP and drop legacy format

Migrate to android.bp as test need to use the library.
As bp do not support conditional statement, and this format has been
deprecated for 3 years, drop the pre-treble .conf parser.

AUDIOSERVER_MULTILIB is no longer use as it does not make sense for a
static lib.

Bug: 114303641
Bug: 111681420
Test: compile, boots
Change-Id: I9f429b306ecfbb80116445ba6297a4b3d6dc57f6
Signed-off-by: Kevin Rocard <krocard@google.com>