Remove discover from test-requirements
Remove discover from test-requirements

It's only needed for python < 2.7 which is not supported

Change-Id: I79b4a2c6591585f45ed10d2cd13a8d6846185b31

openstack/osprofiler,openstack/osprofiler,openstack/osprofiler,stackforge/osprofiler,stackforge/osprofiler,stackforge/osprofiler