audio: Skip tests if audio HAL service lacks "primary" device

Non-default audio service (e.g. MSD) is allowed not to have
a "primary" device. In this case tests that require it can be
skipped.

Manage static objects of a test suite in a canonical gtest way
using SetUp/TearDownTestSuite.

Bug: 139321356
Bug: 141433379
Test: vts-tradefed run commandAndExit vts -m VtsHalAudioV5_0Target
      on a device with "msd" audio HAL module

Change-Id: I08a11b2caa9a913e812f1c203007070e4e68c44e