[AudioPolicy][Engine] Attributes of strategy not populated

The assistant new stream CL has broken the strategies without
stream types. The attributes are not populated anymore preventing
to retrieve the volume group from attributes.

Bug: 136121584
Test: run cts-dev -m CtsMediaTestCase --test android.media.cts.AudioProductStrategyTest
run cts-dev -m CtsMediaTestCase --test android.media.cts.AudioVolumeGroupTest
run cts-dev -m CtsMediaTestCase --test android.media.cts.AudioVolumeGroupChangeHandlerTest
run cts-dev -m CtsMediaTestCase --test android.media.cts.AudioManagerTest#testPermissionsForVolumePerAttributes
run cts-dev -m CtsMediaTestCase --test android.media.cts.AudioManagerTest#testGetAndValidateProductStrategies
run cts-dev -m CtsMediaTestCase --test android.media.cts.AudioManagerTest#testGetAndValidateVolumeGroups
run cts-dev -m CtsMediaTestCase --test android.media.cts.AudioManagerTest#testSetGetVolumePerAttributesWithInvalidAttributes
run cts-dev -m CtsMediaTestCase --test android.media.cts.AudioManagerTest#testSetGetVolumePerAttributes
run cts-dev -m CtsMediaTestCase --test android.media.cts.AudioManagerTest#testVolumeGroupCallback

Change-Id: I15a14e4cf85e6c4bbf09db24bb33b4b9fb9cab54
Merged-In: I15a14e4cf85e6c4bbf09db24bb33b4b9fb9cab54
Signed-off-by: François Gaffie <francois.gaffie@renault.com>