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

Change-Id: Ife92cc76cd3b3d9887130d717c0910df8e13e961

openstack/networking-cisco,noironetworks/networking-cisco,Tehsmash/networking-cisco,Tehsmash/networking-cisco,openstack/networking-cisco,noironetworks/networking-cisco