Add com.android.bluetooth.updatable to resolver apex_available

Changing dnsresolver_aidl_interface-V2-java to
dnsresolver_aidl_interface-unstable-java in upcoming CL.
Module com.android.bluetooth.updatable requires
"dnsresolver_aidl_interface-unstable-java" that is not
available for the APEX. Add com.android.bluetooth.updatable
to resolver apex_available that let
com.android.bluetooth.updatable uses previous
dnsresolver_aidl_interface-V2-java.

Bug: 149733540
Test: m -j
Change-Id: I0deb117ac7600973f97aff7a5606363fc1a00a94