Run a shell script instead of tox for osc functional

Currently, when running functional tests for OSC, we try to run
a tox job. It automatically fails because the user running tox does
not have sufficient permission to run the tests.

Suggest just running a single script file that OSC maintains, rather
than having to change infra resources every time something changes.

Change to add functional tests for OSC is here:
https://review.openstack.org/#/c/122605/

Change-Id: I8543db1c2ecbb6f78eb831ebc9ea1a03625e3542
Merge "Run a shell script instead of tox for osc functional"