Restrict creation of secondary users CTS tests

Background
* Secondary users should be disabled
  when the device is an organization-owned
  managed profile device.
* This is because supporting secondary
  users would complicate the semantics of
  user restrictions.

Changes
* Add CTS test to ensure secondary user
  cannot be added.
* Modify CTS tests that previously created
  secondary users.
* Remove CTS tests that applied the
  DISALLOW_ADD_USER restriction.

Manual Testing Steps
* Provision an organization-owned managed
  profile device.
* Check Settings > System > Multiple users
  and verify that a user cannot be added.
* Check WP TestDPC 'Set user restrictions
  on parent' and verify 'Disallow add user'
  is not present.

Bug: 155281701
Test: Manual testing
      atest com.android.cts.devicepolicy.OrgOwnedProfileOwnerTest#testCannotAddSecondaryUser
      atest com.android.cts.devicepolicy.OrgOwnedProfileOwnerTest#testUserRestrictionsSetOnParentAreNotPersisted
      atest com.android.cts.devicepolicy.OrgOwnedProfileOwnerTest#testDevicePolicyManagerParentSupport
Change-Id: Ib17f0b87c989f84bdacd9cffa5b10d81dae6e033
3 files changed