VTS: Do not require XML for Audio effect V2

In O, the Audio effect V2 HAL allows not to have an audio effect XML
configuration but to use a .conf format.

In P, before this patch, the Audio effect V2 HAL _requires_ to have an
audio effect XML configuration and forbids the use of a .conf format.

This is discouraged by Treble as it means that an unchanged HAL V2
implementation that was compatible with O VTS will not be with P VTS.

As a result, revert to the Oreo behavior for Audio Effect V2 VTS.

Note that the audio effect V4 VTS is not changed by this patch and
still requires an audio effect XML configuration.
Aka device _updating_ to P will not have to upgrade to XML but new
devices lunching on P are still required to have an audio effect
XML configuration.

This commit only changes VTS code.

Test: cd hardware/interfaces/audio/effect/
      mmm 2.0/vts/functional 4.0/vts/functional && adb sync data
      adb push *.0/xml/audio_effects_conf_V*.xsd /data/local/tmp/
      adb shell
      cd /data/nativetest64
      OPS=--gtest_filter=CheckConfig.audioEffectsConfigurationValidation
      VtsHalAudioEffectV2_0TargetTest/VtsHalAudioEffectV2_0TargetTest $OPS
      VtsHalAudioEffectV4_0TargetTest/VtsHalAudioEffectV4_0TargetTest $OPS
      rm /{odm,vendor,system}/etc/audio_effects.xml || true
      VtsHalAudioEffectV2_0TargetTest/VtsHalAudioEffectV2_0TargetTest $OPS
      ! VtsHalAudioEffectV4_0TargetTest/VtsHalAudioEffectV4_0TargetTest $OPS
Bug: 111421676
Change-Id: Ifb15d65ae4aa65759c8ebaa91cbc8c02234030dc
Merged-In: Ifb15d65ae4aa65759c8ebaa91cbc8c02234030dc
Signed-off-by: Kevin Rocard <krocard@google.com>
(cherry picked from commit b41b5754)