Make test for activity page more thorough
Make test for activity page more thorough

This commit paramaterizes the test for the activity page, so that it
checks all combinations of template type and notification status.

gov-cjwaszczuk/notifications-admin,alphagov/notifications-admin,alphagov/notifications-admin,alphagov/notifications-admin,gov-cjwaszczuk/notifications-admin,alphagov/notifications-admin,gov-cjwaszczuk/notifications-admin,gov-cjwaszczuk/notifications-admin