C2 VTS: Enable AdaptiveBitrateTest only for CDD mandated encoders am: 15ccfa68a8 am: e5ac6fbdaa am: aee1acb55a

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

Change-Id: Iba751d3ada1df74b7873256e5d21e5fbb2f0b792