Remove / Rename ocw_next variables

[ChristopherChudzicki]

Description/Context

There are a few lingering references to OCW_NEXT env vars that are no longer in use. (For example, in app.json.). Additionally, some variables that are in use are named ocw_next but should just be OCW.

• Remove OCW_NEXT variables not in use, e.g., app.json
• Rename ocw_next variables in apps that are still in use (learning_resources, learning_resource_search). Example: https://github.com/mitodl/mit-open/blob/3b55e0e8057a7a5916a975133680a3a9f8d3330a/learning_resources/conftest.py#L104
  • We can leave the ones in course_catalog... We should delete that whole app at some point.
• Rename this webhook url https://github.com/mitodl/mit-open/blob/3b55e0e8057a7a5916a975133680a3a9f8d3330a/learning_resources/urls.py#L114