Fix bug in createAndManageUser on non hsum devices

The recent changes for blocking createAndManageUser accidentally blocked it even on non-hsum devices if the DPC had specified the single_user mode in its manifest.

Bug: 336547982
Test: atest com.android.cts.devicepolicy.DeviceOwnerTest
Change-Id: I937c68eb1a6eef6cc26e18d7f17f651e4dac072e
1 file changed