Resolve READ_PRIVILEGED_PHONE_STATE bypass

Fixes a bug where the calling user id was not being passed to the default dialer cache due to the calling identity being cleared (resulting in the Telecom process being used to check what the default dialer is).

Bug: 373862149
Change-Id: Icb59debc225a1963dd0a37f2e1f025e764715e0e
Test: Manual (patch also verified by reporter)
Flag: EXEMPT bugfix