Migrate `Category:Git LFS` to Category:Source Code Management`

Summary

This template is for new or renaming Category labels. This review helps to ensure there will be no impact with triage automation and reports.

Action items

• Link the merge request to www-gitlab-com for the category.yml change
• (If applicable) Label migration on existing issues and merge requests: apply the new label to opened & closed issues, and open & merged merge requests.
• (If applicable) Rename the old label by adding [DEPRECATED] at the end of the label name, like ~"CI/CD [DEPRECATED]".

/cc @gitlab-org/quality/engineering-productivity