CarrierServiceBindHelper: incorrect user unlocked event received in HSUM

This CL fixes the issue that CarrierServiceBindHelper always register to
receive ACTION_USER_UNLOCKED from system user by registering the
receiver for current user instead.

It keeps the same behavior for non-HSUM devices but let secondary users
(e.g. Main user) in HSUM receive the event for current user.

Bug: 345523452
Test: atest FrameworksTelephonyTests
Test: CarrierService regressoin test on both Phone andd Tablet
Flag: com.android.internal.telephony.flags.support_carrier_services_for_hsum
Change-Id: Ice803050271f720dee6bfb2177fe5197bf67c7ed