Always set pip vars for tempest install

In stable/rocky, there is no distro install method for os_tempest
so it will always install from source. However, in distro installs
there is no repo container and no constraints are set, so the
tempest installation is currently unconstrained which delivers
inconsistent results from one day to the next.

To ensure that the installation is constrained properly, we make
sure that the pip vars are set and the correct vars are used when
installing tempest.

Given that the tempest_ vars in distro_install are not used, we
remove them from the file to reduce confusion.

Change-Id: I851e50902d3866f8f28ebc6f172bc61d0a4778c3

playbooks/defaults/distro_install.yml

@@ -59,8 +59,6 @@ sahara_install_method: distro
 searchlight_install_method: distro
 swift_install_method: distro
 tacker_install_method: distro
-tempest_install_method: distro
-tempest_bin: /usr/bin
 trove_install_method: distro
 watcher_install_method: distro
 zaqar_install_method: distro
@@ -68,5 +66,3 @@ zun_install_method: distro
 
 # default variables for PIP since we are not using the repo server
 pip_default_index: "https://pypi.python.org/simple"
-
-tempest_venv_download: false

playbooks/os-tempest-install.yml

@@ -18,7 +18,12 @@
   gather_facts: "{{ osa_gather_facts | default(True) }}"
   user: root
   vars_files:
-    - "defaults/{{ install_method }}_install.yml"
+    - defaults/repo_packages/openstack_services.yml
+    - defaults/source_install.yml
+  vars:
+    tempest_venv_download: "{{ install_method == 'source' }}"
+  pre_tasks:
+    - import_tasks: common-tasks/set-pip-vars.yml
   roles:
     - role: "os_tempest"
     - role: "system_crontab_coordination"