Remove obsolete tempest-lib
Remove obsolete tempest-lib

tempest-lib has been reintegrated into tempest and this repository
already uses tempest instead of tempest-lib. Replace requirements for
tempest-lib with requirements for tempest.

See also
https://specs.openstack.org/openstack/qa-specs/specs/tempest/implemented/reintegrate-tempest-lib.html

To fix building, we need to add os-testr to get subunit-trace as requirement.

Change-Id: I9dff73a03c7e8ebabdf04afe0ac48d74842f1c7c

stackforge/networking-ovs-dpdk,stackforge/networking-ovs-dpdk,openstack/networking-ovs-dpdk,stackforge/networking-ovs-dpdk,openstack/networking-ovs-dpdk