Merge branch 'doc-gitaly-remove-outdated-references' into 'master'

Remove unsupported GitLab versions from Gitaly docs

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/149267



Merged-by: Evan Read <eread@gitlab.com>
Approved-by: Evan Read <eread@gitlab.com>
Reviewed-by: Evan Read <eread@gitlab.com>
Reviewed-by: Hubert Maraszek <hmaraszek@gitlab.com>
Co-authored-by: Hubert Maraszek <hmaraszek@gitlab.com>