Add instructions on how to remove v1 package metadata

Why are we doing this work

As mentioned in the following thread of the ingestion MR, it should be possible for users with the old uncompressed dataset to remove the old data in order to reduce their database size !120027 (comment 1394462482)

Proposal

Add instructions on how to remove old dataset data to the documentation. Add link to the documentation in the release post.

Implementation plan

• Update documentation on license scanning https://docs.gitlab.com/ee/user/compliance/license_scanning_of_cyclonedx_files/
  • Add instructions on how to remove data in the PackageVersionLicense and PackageVersion models.
• Remove data warning (i.e. "The full package metadata sync can add up to 30 GB to the PostgreSQL database") from https://docs.gitlab.com/ee/administration/settings/security_and_compliance.html#choose-package-registry-metadata-to-sync