Fix One-handed mode truncated screen when device rotates in

multiple user mode

User id mismatch when switching to multi-user, refactor some
switch multiple user code.

Bug: 199748164

Test: Manually switch to multiple users to test.
Test: atest WMShellUnitTests
Change-Id: I6ac4d13c5251141d2c65a3ef2b6e2f1f0ca0f650