The tests removed here are now available in the Tempest plugin inside
sahara-tests.
Also remove few test dependencies which are not needed anymore (as a result
of this code removal but also of previous changes).
Change-Id: I6394cd0ed01d7799ba303fd36e4777018de16854
Use the Tempest plugin interface for python client tests (which
are already tempest-based) instead of copying the tests inside
the tempest tree.
Inspired by the same type of change applied to Manila,
see Ie5ed64a6777ed1acf8dd56522c26705ae897596d
Depends-On: I06f1e13207cc6d661c078c4c4cf1ae7974ecf3da
Change-Id: I6073a528413aefd96882179a1eb8bbe715c6417b