Revert addition of LICENCE.md symlink

Description

Reverts f7e6089a which added a symlink from LICENSE.md to the BSD3 license file. This does not work as expected in the web GUI. It is a known issue - https://gitlab.com/gitlab-org/gitlab/-/issues/15093

Checklist

• Contribution meets RAL's licence terms
• Documentation updated
• [NA] clang-format and clang-tidy run and changes included (C/C++ code)
• [NA] flake8 run and changes included (Python code)
• Commit message includes information on how to reproduce the issue(s)
• [NA] Tests added or updated
• [NA] Tests pass when run with AddressSanitizer