Remove setup_client method

It is unnecessary to add setup_clients classmethod and create a new
variable for the client. I is more clear to use the original client name.
The client name 'client' is too much general compare to 'volumes_client'
and 'snapshots_client'.

Change-Id: I68a605ef2e1f893d54724c226512a0cbfa8f4bb2
8 files changed