This patch updates our tox_install_project.sh script to account for zuul
v3 changes. The changes are made to be backwards compatible so the
script should also still work with zuul v2 jobs. Also see the depends on
patch for the project-config changes needed for our zuul v3 support.
Depends-On: Icd0dfdef3486be95ef45beb9ea96767f731d9e9e
Change-Id: Ic0d25e9f9e6d1fe7cba7cae93e66dbbc08c12071