Remove the support for legacy ASHA streaming over UIPC

The Bluetooth APEX is no longer bound to provide compatibility
with the legacy HAl (UIPC based) now that HIDL has been a
requirement since Android 8+.

Bug: 331817295
Test: m com.android.bt
Flag: EXEMPT, dead code removal
Change-Id: If4bc4c8c9e94ac81f6ca21fbae1500b71def7b82