C2 VTS: Enable AdaptiveBitrateTest only for CDD mandated encoders am: 15ccfa68a8 am: e5ac6fbdaa am: aee1acb55a am: a9382770e8 am: e9ff771cb8

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

Change-Id: Ie0f1648b814d2caa8ac169a3057ae3a6b9e3dba0