fix: Adds url negation regex for course id

[brobro10000]

Description

This ticket adds a negation endpoints regex to strip from captured course_ids. Since some URLs being parsed do not contain a run, the existing regex in place captures additional URL strings that are not pertinent to a course_id.
This PR adds a negation regex to strip out endpoints that may appear in URLs where a run is not included as part of the course_id. The implementation of including a negation regex as opposed to modifying the original regex was an intentional decision to improve the extensibility of adding additional negation routes if need be.

Useful information to include:

• Which edX user roles will this change impact? Common user roles are "Learner", "Course Author",
  "Developer", and "Operator".
• Include screenshots for changes to the UI (ideally, both "before" and "after" screenshots, if applicable).
• Provide links to the description of corresponding configuration changes. Remember to correctly annotate these
  changes.

Supporting information

https://2u-internal.atlassian.net/browse/ENT-9770

Testing instructions

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Deadline

"None"

Other information

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• Does this change depend on other changes elsewhere?
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