If user and sign-in screen both have automatic detection turned on, and last time zone detection succeeded, we should copy it's value from the sign-in screen to user session, and from user session to the sign-in screen.

Current behavior (with completely separate settings) surprise users, as automatically detected time zone on the sign-in screen will change to the previous location after entering user session. And it will take another detection round to set in-session time zone correctly.

And the same issue appears when user signs out and previous sign-in screen time zone could be applied. This surprises Enterprise users, as they are not device owners.