To avoid overriding important "pip_install_options" that apply to all
hosts, we should move the pip_install_option to the central tests
repository.
This happens as part of the following PR:
https://review.openstack.org/381023
This PR removes the override from nova.
Change-Id: Ifc69924d154b0c56b760cd8b2e22b5a838b37289
Depends-On: I1c25e2c95e3bd5aca02b6220f82cf577ccfdbc8b
(cherry picked from commit be678ea6be)