License compliance report shows legacy approval_status [backend]

Summary

When generating a report comparison the classification of a license uses legacy classification names.

See this thread for more information.

These should be converted to the expected classifications: https://gitlab.com/gitlab-org/gitlab/blob/f385377cf38d187f138885af984a7d66f3628e0f/ee/app/models/software_license_policy.rb#L9

What is the current bug behavior?

approval_status is reported as legacy name (e.g. blacklisted, approved).

What is the expected correct behavior?

approval_status should return non-legacy name (denied, allowed).

Implementation plan

1. Rename approval_status into legacy_approval_status and use it in EE::Entity::ManagedLicense we need this to ensure no breaking changes in API, as that will be tackled separately in #335707 (closed)
2. Create a feature flag
3. Hide under feature flag lc_remove_legacy_approval_status new behavior of approval_status so it returns classification.
4. Update tests that will fail:
   1. ee/spec/controllers/projects/pipelines_controller_spec.rb:107
   2. ee/spec/models/software_license_policy_spec.rb
5. Fix https://gitlab.com/gitlab-org/gitlab/-/blob/033101d9a98b2338038c87ec0356de10222a180d/ee/app/models/ee/merge_request.rb#L183 and remove legacy names

Testing

• update merge request widget spec to disable feature flag (should be turned on after #335868 (closed))

SET to test E2E tests with the feature flag set and unset.