Audio HAL VTS: Improve ASSERT of Result and Return

Previously tests on Result and Return were using ASSERT_NO_FATAL_FAILURE
and helper methods.
This leaded to complex error messages were the error did not pointed to
the helper methods instead of the ASSERT_RESULT call.
Additionally SCOPE_TRACE messages are repeated
for each ASSERT_NO_FATAL_FAILURE level.

Use ::testing::AssertionResult to improve drastically the error messages.

Test: vts-tradefed run vts --module VtsHalAudioV2_0Target
Test: call/play music/record/video...
Bug: 36311550
Change-Id: If705502546606d678df3f1966b0cd9f3ef8c2529
Signed-off-by: Kevin Rocard <krocard@google.com>