Remove PackageManager.getResourcesForApplicationAsUser API

To switch another user to do something should create the context of the
specified user by using Context.createContextAsUser rather than call
*AsUser API directly.

This patch replaces the usage of
PackageManager.getResourcesForApplicationAsUser in SystemUI.

Test: make -j droid cts gts vts
Test: make -j docs
Test: atest SystemUITests \
    FrameworksServicesTests:com.android.server.pm
Bug: 170928809
Change-Id: Ie31d772a5002f349d8dd0e0ec8fe6134b1895517