Update isAuthenticated before authentication event is emitted

Convert the flow to a state flow as we need that for the child CL.
Emitting the authentication status first results in the collectors running before `isAuthenticated` flow is updated.

Bug: NA
Test: unable to replicate the same coroutine behavior in a unit test.
Flag: LEGACY FACE_AUTH_REFACTOR ENABLED
Change-Id: Ie258205863ccaafe3215309fd7b40691b2263f60