TIF: fix display issue with input panel in kid profile

When switching to kids profile, startUser is triggered instead of
switchUser. Current userId was not updated in startUser, making input
panel in kids profile not able to update correctly. This change updates
current userId in startUser.

Test: manual tetsing on device
Bug: b/356642594, b/318577846, b/349534794, b/244688962
Flag: EXEMPT bugfix
Change-Id: I842755064395c26886642fedc96cb96365efafa0