Remove hplefthandclient from global-requirements

The need for hplefthandclient in tests was removed in
https://review.openstack.org/#/c/93363/ so now we
can remove it from global-requirements.

Change-Id: I8442d64f8826a88956642ff360a1107a4814a8c1
Merge "Remove hplefthandclient from global-requirements"