Fix devicePresence no callback after reboot

Executes mDevicePresenceProcessor.init() upon PHASE_BOOT_COMPLETED.
This change addresses the issue of prematurely initiating BLE/Bluetooth
scans during PHASE_SYSTEM_SERVICES_READY, when the Bluetooth service may not be fully operational

Test: cts
Bug: 349858260
Flag: EXEMPT bugfix
Change-Id: Ia0b3be5fcc0005bb4d5b7d2654b6ebb64c7cddb6