Added support for installing tempestconf from distro

On Red Hat, python-tempestconf is a dependency of
openstack-tempest and on SUSE, it is a seperate package and can
be installed on SUSE distro job only when tempest_use_tempestconf
is set to true there. On Ubuntu, we are running tempest from
source, so we donot need to make any change there.

Depends-On: https://review.openstack.org/#/c/625545/

Change-Id: I1644685a3aa263f74eada36b67f9d624e6393ddd

tasks/tempestconf.yml

@@ -20,10 +20,14 @@
     venv_install_destination_path: "{{ tempest_tempestconf_venv_bin | dirname }}"
     venv_pip_install_args: "--isolated"
     venv_pip_packages: "{{ tempest_tempestconf_pip_packages }}"
+  when: tempest_install_method == 'source'
 
 - name: Executing python-tempestconf
   shell: |
+    set -e
+    if [ -d {{ tempest_tempestconf_venv_bin }} ]; then
     . {{ tempest_tempestconf_venv_bin }}/activate
+    fi
     export OS_AUTH_URL="{{ keystone_service_internaluri }}"
     export OS_IDENTITY_API_VERSION="3"
     export OS_USERNAME="{{ keystone_admin_user_name }}"

vars/suse.yml

@@ -31,3 +31,4 @@ tempest_plugin_distro_packages:
   - "{{ (tempest_service_available_ironic | bool) | ternary('python-ironic-tempest-plugin', '') }}"
   - python-keystone-tempest-plugin
   - "{{ (tempest_service_available_neutron | bool) | ternary('python-neutron-tempest-plugin', '') }}"
+  - "{{ (tempest_use_tempestconf | bool) | ternary('python-tempestconf', '') }}"