[Multi-user] Change device provisioned to per-user setup complete

Migrate from the global setting DEVICE_PROVISIONED to the per-user
setting USER_SETUP_COMPLETE. The logic for how the service handles
provisioned state is the same, only the setting we use to determine the
state is changed, as well as a rename to reflect this ("provisioned" ->
"setup complete").

ProvisionedObserver is now SetupObserver (move didn't persist b/c of
amount of changes to the file)

The BackupManagerMonitor log event id referencing provisioned will be
changed in a future CL as it requires an API change.

Bug: 121305979
Test: 1) atest RunBackupFrameworksServicesRoboTests
2) Reset device, go through SUW -> not setupComplete;
Finish SUW -> setupComplete (verify logging + dumpsys) and jobs
scheduled;
Perform backup (not blocked by setupComplete);
Add new user -> setupComplete only after finishing SUW

Change-Id: Iddf9ce7853a13b2d51135047de1b270af7034c06