Multiple 403 errors in QA tests due to leaking state in tests

!102477 (merged) has introduced a new shared_context which is automatically required by in /gitlab/qa/spec/spec_helper.rb:5 this may be overriding imported_project, user, group etc and causing other tests to fail.

These failures can be identified by a reference to /qa/specs/features/shared_contexts/github_import_shared_context in the error stack trace e.g. https://gitlab.com/gitlab-org/gitlab/-/jobs/3254833031#L1874

Should be fixed by revert MR !102600 (merged)