Add new version of createUser performance test

Similar to what was done for switchUser, this commit adds a new version
of the createUser test. In this variation, a wait for cool down was added
in between iterations.

Bug: 261621873
Test: atest UserLifecycleTests#createUser_realistic
Change-Id: I6235c782254b2a19f9990994b664ad9ac5c6f2ce