BufferQueues: clean up ConsumerBase constructors

These currently use flags that muddy up client code. We've added nice
new *::create methods, so lets use those and clean
things up.

BYPASS_IGBP_IGBC_API_REASON=warren buffers

Bug: 398822412
Flag: EXEMPT refactor
Test: builds, presubmit
Change-Id: I57b5ad3e0214b4580d195eb451f707f3a3c912a6