Replaced UserManager.getUsers(excludeDying) by getAliveUsers()

The existing method is confusing (the argument used to be called
includeDying) and it puts the burden on the caller (which need to
understand what the parameter means).

Furthermore:

- The majority of calls are for getUsers(excludeDying=true).
- The calls for getUsers(excludeDying=false) are equivalent to
  calls to getUsers()

So, a previous CL deprecated getUsers(excludeDying) and this CL
replaces all remaining getUsers(true) calls to getAliveUsers() - calls
to getUsers(false) were already refactored to call getUsers() in a
previous CL.

Test: m
Test: a RollbackTest VpnTest ConnectivityServiceTest PermissionMonitorTest UserSettingsTest AppInfoDashboardFragmentTest UserHelperTest

Bug: 157921703

Change-Id: I94973c91c14ad47c43cc1168ab766dc9e2815e54
Exempt-From-Owner-Approval: owners approval lost after rebase