C2 VTS: Enable AdaptiveBitrateTest only for CDD mandated encoders am: 15ccfa68a8 am: e5ac6fbdaa am: 3d74f2bde0 am: e20f78ca11 am: 0c3cc4333b

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

Change-Id: Ife301bd5b7f59ddc51f1bec5a6906028cbe7ade6