Return a fully-qualified app_profile string.

def app_profile_path(cls, project, instance, app_profile):
        """Return a fully-qualified app_profile string."""
        return google.api_core.path_template.expand(
            "projects/{project}/instances/{instance}/appProfiles/{app_profile}",
            project=project,
            instance=instance,
            app_profile=app_profile,
        )