Depend on corresponding server in WaitCondition

most of the templates used in scenario tests already do this
to exclude unpredictable (especially in virtualized cloud CI environments)
server boot from the wait condition timeout, however 3 templates
(used in 3 tests) are missing this at the moment.

This patch adds an explicit depends_on on the server that the
WaitCondition is waiting for in all scanario templates that use
WaitConditions.

Change-Id: I43d5b3862970db5217651b570525f696910bf320

heat_tempest_plugin/tests/scenario/templates/test_server_signal.yaml

@@ -108,6 +108,7 @@ resources:
 
   wait_condition:
     type: OS::Heat::WaitCondition
+    depends_on: server
     properties:
       handle: {get_resource: wait_handle}
       timeout: {get_param: timeout}

heat_tempest_plugin/tests/scenario/templates/test_volumes_create_from_backup.yaml

@@ -97,6 +97,7 @@ resources:
 
   wait_condition:
     type: AWS::CloudFormation::WaitCondition
+    depends_on: instance
     properties:
       Count: 1
       Handle: { get_resource: wait_handle }

heat_tempest_plugin/tests/scenario/templates/test_volumes_delete_snapshot.yaml

@@ -107,6 +107,7 @@ resources:
 
   wait_condition:
     type: AWS::CloudFormation::WaitCondition
+    depends_on: instance
     properties:
       Count: 1
       Handle: { get_resource: wait_handle }