Remove Coursegraph from edx-platform

[feanil]

Remove coursegraph and the neo4j dependency from edx-platform.

This is part of this depr: #34342

Comment on the above ticket when the PR is up for review and when the PR has been merged.

Once the PR merges, update the Sumac release notes page under https://openedx.atlassian.net/wiki/spaces/COMM/pages/13205845/Open+edX+Release+Planning

[qasimgulzar]

here we already have a PR

[feanil]

Thanks @qasimgulzar , hopefully we can just rebase that and land it.

[qasimgulzar]

@feanil I just rebased the branch probably you can give it a look now.

[feanil]

Looks like 2U is still using this old infrastructure and so we should hold of till May 27, 2024 to merge this PR.

[feanil]

This was merged via #34417 and so this and the related DEPR can be marked as completed.