[#13498] Remove "archive courses" back-end logic

[TobyCyan]

Part of #TEAMMATES#13498

Outline of Solution

• Removed course archival from logic and entity classes.
• Removed archive field data migration class.
• Updated tests.

Upstream #PR

[github-actions]

Hi @TobyCyan, thank you for your interest in contributing to TEAMMATES!
However, your PR does not appear to follow our contribution guidelines:

• Description must reference the issue number the PR is fixing, e.g. Fixes #<issue-number> (or Part of #<issue-number> if the PR does not address the issue fully)

Please address the above before we proceed to review your PR.