Update Openstack, add missed steps to upgrade computes

Additional changes:
 * Refactored switch_to_proposed_pipelines to avoid multiply executions

Change-Id: If9b0c460bdbf41b8248dc3cb5f0d2f486b47e954
diff --git a/tcp_tests/fixtures/salt_fixtures.py b/tcp_tests/fixtures/salt_fixtures.py
index 226ab22..d662180 100644
--- a/tcp_tests/fixtures/salt_fixtures.py
+++ b/tcp_tests/fixtures/salt_fixtures.py
@@ -21,7 +21,7 @@
 LOG = logger.logger
 
 
-@pytest.fixture(scope='function')
+@pytest.fixture(scope='session')
 def salt_actions(config, underlay_actions):
     """Fixture that provides various actions for salt