Set ro.device_owner when DO is present.

Do not wait until deivce_provisioned is set. This logic is currently used
for Wear devices and since nothing except security logging now depends on
this property, we can safely set it to "true" if there is a DO on the device.

Bug: 35342467
Test: manual, setting a DO before SUW triggers setting of the property.
      property to be set.
Test: cts-tradefed run cts -m CtsDevicePolicyManagerTestCases -t com.android.cts.devicepolicy.DeviceOwnerTest

Change-Id: I2c179194fb8f0f4bef96bb21dbf2522ba99afcec