Add screenshots for:

/clouds/openstack/{cloud_context}/server_group/add /clouds/openstack/{cloud_context}/server_group /clouds/openstack/{cloud_context}/server_group/{openstack_server_group}/delete

Closes #3408933

modules/cloud_service_providers/openstack/tests/src/Behat/features/templates/OpenStack-ATDD-03-04-OperateServerGroups.feature

@@ -6,6 +6,7 @@ Feature: Create, read, and delete a server group for OpenStack
     Given I am logged in as a user with the "Administrator" role
     When I visit "/{{ root_path }}/openstack/{{ cloud_context }}/server_group/add"
     And I wait {{ wait_render }} milliseconds
+    And I take screenshot
     And I should see the heading "{{ prefix_add_form }} server group"
     And I enter "{{ server_group_name_operate }}" for "Name"
     And I enter "{{ server_group_policy }}" for "Policy"
@@ -23,6 +24,7 @@ Feature: Create, read, and delete a server group for OpenStack
     Given I am logged in as <role>
     When I visit "/{{ root_path }}/openstack/{{ cloud_context }}/server_group"
     And I wait {{ wait_render }} milliseconds
+    And I take screenshot
     And I should see the link "{{ server_group_name_operate }}"
     And I wait {{ wait }} milliseconds
     And I click "{{ server_group_name_operate }}"
@@ -50,6 +52,7 @@ Feature: Create, read, and delete a server group for OpenStack
     Then the url should match "/{{ root_path }}/openstack/{{ cloud_context }}/server_group/"
     And I click "Delete" in the actions
     Then the url should match "/delete"
+    And I take screenshot
     And I press "Delete"
     And I wait {{ wait_render }} milliseconds
     Then I should be on "/{{ root_path }}/openstack/{{ cloud_context }}/server_group"