Port standalone job to os_tempest

Changing tripleo-ci-centos-7-standalone job to use os_tempest instead of
validate-tempest role to execute tempest tests.

https://tree.taiga.io/project/tripleo-ci-board/task/1032

Change-Id: I6473405025623d0dbd5347a4e348f4bbb9635894

zuul.d/standalone-jobs.yaml

@@ -11,7 +11,17 @@
     vars:
       featureset: '052'
       featureset_override:
+        run_tempest: false
         tempest_format: container
+        tempest_run_concurrency: 2
+        tempest_tempest_conf_overrides:
+          auth.use_dynamic_credentials: true
+        tempest_test_whitelist:
+          - 'tempest.scenario.test_minimum_basic.TestMinimumBasicScenario'
+          - 'tempest.scenario.test_network_basic_ops.TestNetworkBasicOps'
+          - 'tempest.scenario.test_volume_boot_pattern.TestVolumeBootPattern'
+          - '\[.*\bsmoke\b.*\]'
+        use_os_tempest: true
     irrelevant-files:
       - ^.*\.md$
       - ^.*\.rst$
@@ -33,6 +43,9 @@
     override-checkout: 'stable/rocky'
     vars:
       branch_override: 'stable/rocky'
+      featureset_override:
+        run_tempest: true
+        use_os_tempest: false
 
 - job:
     name: tripleo-ci-fedora-28-standalone