Delete tests.baremetal.util.new_bm_deployment()

The function is not used anymore. It creates an instance of
BareMetalDeployment, which was removed in c20110d1.

Change-Id: I40b634f8cf0d4369f09cb61aca6f95a059e85d6d
Merge "Delete tests.baremetal.util.new_bm_deployment()"