VtsHalDrmV1_0Target test failure

The DrmHalVendorPluginTest.RestoreKeysClosedSession test wasn't
taking into account the policy of the asset, so both streaming
and offline assets were included in the test which is incorrect.

Test: drm vts test passes

bug:37358379
Change-Id: I41116e77a1ae306bb1a484e3714360c8553590f0