Before edx-platform version 19ba691, only `lms_web_url` was exposed from the course blocks API. Now that the API also exposes `legacy_web_url`, we can stop falling back to `lms_web_url` when `legacy_web_url` is absent. TNL-7796
Before edx-platform version 19ba691, only `lms_web_url` was exposed from the course blocks API. Now that the API also exposes `legacy_web_url`, we can stop falling back to `lms_web_url` when `legacy_web_url` is absent. TNL-7796