C2VdaBqBlockPool: C2VdaBqBlockPoolData inherits C2BufferQueueBlockPoolData

Originally, the definition of C2BufferQueueBlockPoolData is hidden at
cpp file. C2VdaBqBlockPoolData has to handle the ownership transition
itself with extra workaround.

At ag/13473071, we expose C2BufferQueueBlockPoolData at header file.
This CL makes C2VdaBqBlockPoolData inherit C2BufferQueueBlockPoolData
directly. With this CL, C2VdaBqBlockPoolData could share the same
logic of the ownership transition.

Bug: 174188958
Test: android.media.cts.AdaptivePlaybackTest

Change-Id: Ib73b2f8bc36bbd9724523624415551a7efadda73