Remove implementation details from bluetooth hidden api flags

Ran the following to compute the set of split_packages and
package_prefixes properties.
    m analyze_bcpf && analyze_bcpf --bcpf com.android.bluetooth-bootclasspath-fragment --fix

Ignore-AOSP-First: com.android.bluetooth-bootclasspath-fragment is not present in AOSP.
Bug: 194063708
Test: m out/soong/hiddenapi/hiddenapi-flags.csv
Change-Id: Icb1c8a6732971dfb35394c09cc8923dd37ab7207