fix: remove slashmark (#287)

[pdpinch]

cherry-picked from edx-platform/master https://github.com/openedx/edx-platform/commit/cfdbb4c951eb25a1e3253d0e9ec5ec441c71ec15

Co-authored-by: connorhaugh chaugh21@amherst.edu

Related Ticket:

https://github.com/mitodl/mitxpro/issues/2332

Description

This PR cherry-picks one of the fixes merged in master in the Download Report section on Instructor Dashboard where a double slash(//) in Course Blocks API call was ending in a 404 in the backend.

Supporting information

There were some other PRs(https://github.com/openedx/edx-platform/pull/29699 & https://github.com/openedx/edx-platform/pull/29742) opened up to fix the issue at hand, but we are going with the one that has already been merged in master.

Testing instructions

• Same as mentioned in https://github.com/openedx/edx-platform/pull/29699 except that you need to be on the maple branch. xpro/maple in this specific case.

[pdpinch]

I think if we rebase this it will clear the lint error.

[pdpinch]

I was hoping that the upstream PR would merge soon, but I think we've run out of time.