Remove support for LDAC decoder

The LDAC decoder is currently loaded as the shared library
libldacBT_bco.so. This will no longer be supported when
bt becomes a mainline module as using dlopen() is
forbidden.

Bug: 331817295
Test: m com.android.bt
Flag: EXEMPT, dead code removal
Change-Id: I3512e59b0f12cf37973aed4275e2c007cb2dcb10