SetupWizard : Ensure we don't override user locale picks

Take scroll events into consideration when deciding whether to override
user locale with sim locale.

Also move locale fetching to be async so we don't cause any unecessary
blocking.

CYNGNOS-1521

Change-Id: I0c4c1b89dd227f661c1a1cdcce445349fe4a206f
(cherry picked from commit 00ad2213)