Use bluetooth.core.gap.le.privacy.enabled sysprop to init BLE Privacy

Replace BLE_LOCAL_PRIVACY_ENABLED with the
bluetooth.core.gap.le.privacy.enabled sysprop from BluetoothProperties.
This enables mainline builds to take BT configurations from the vendor
set sysprops.

Bug: 227605076
Change-Id: I0041f2d7bb39a3130d6efc47a509f9223954e8c1
Merged-In: Ifba555363d37f6d62387911fb97cb230b4551ac4
Test: build and run adt3-userdebug