Rally ships it's own version of upper-constraints [1].
As we move openstack-ansible to using the new pip resolver this
causes several issues. The rally specific version of u-c contains
constraints for pip/setuptools/wheel which will inevitably be in
conflict with those in global-requirement-pins. This results in
several problems.
* Rally is branchless and so applying branch-specific versions
of openstack u-c is incorrect
* Rally should be installed using the rally u-c rather than
openstack u-c
* Rally should not use the repo server to build wheels as the repo
server wheel build venv will have different versions of pip/
setuptools/wheel to those specificed in rally u-c.
* Rally venv build should not be subject to openstack-ansible
global-requirement-pins as these are in conflict with rally u-c.
This patch introduces the changes necessary to build rally in a self
contained manner on the utility host with no use of the repo server.
It also includes a revert of I73887784cbc3ce6089a42c67871dbc6c3d54acf6.
[1] https://opendev.org/openstack/rally-openstack/raw/branch/master/upper-constraints.txt
Change-Id: Idbd71ade1ab82d2d218e560b2f10c38116ff47e3
03c7872536