Require non-partial process user before checking device policy.

This changelist predicates reaching out to device policy for communal
logic until the process user is fully created. This is done to ensure
user static permissions (such as INTERACT_ACROSS_USERS_FULL) are in
place.

Fix: 407646672
Test: atest CommunalSettingsInteractorTest#allowedForCurrentUserByDevicePolicy_reportsFalseWithPartialUserInfo
Flag: EXEMPT bugfix
Change-Id: I536ab5d112d8c25dfcb42021e1e4b1ce35d6dcfb