Set new user's default font weight adjustment to 0

Ideally we would use an undefined value like
Configuration.FONT_WEIGHT_ADJUSTMENT_UNDEFINED to represent the undefined
setting but undefined config values do not trigger configuration updates
(which we need on a user change)

Bug: 174605763
Test: switch to new user
Change-Id: I73e6456427e3f05d02182e9544fe54cd44640e2e