[15.0] Remove legacy approval status names from `managed_licenses` API

Proposal

With #335707 (closed) we deprecated blacklisted and approved statuses in managed_licenses API, now we need to remove them

announcement https://about.gitlab.com/blog/2021/12/13/composition-analysis-group-deprecations/

https://docs.gitlab.com/ee/update/deprecations.html#legacy-approval-status-names-from-license-compliance-api

Implementation plan

1. In managed_licenses api file remove mention of blacklisted and approved statuses as request params.
2. Enable lc_remove_legacy_approval_status feature flag to get new statuses in API response.
3. Update documentation and remove mention of “approved” or “blacklisted” statuses as params.

Testing

SET to update the appropriate E2E Browser UI test for licence compliance when feature flag rolls out.