C2 VTS: Enable AdaptiveBitrateTest only for CDD mandated encoders am: 15ccfa68a8 am: e5ac6fbdaa am: 3d74f2bde0

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/av/+/15898098

Change-Id: I062d42e8ef5cfbccd04baffe05fa647c9f62ebbf