Scope the offline CVE enrichment move step to GitLab 19.4 and earlier

What does this MR do?

This MR scopes the CVE enrichment move step in the offline quick start guide to GitLab 19.4 and earlier, because offline sync in 19.5 reads a copy of the enrichment bucket as it is (!253401 (merged)).

From 19.5 the guide's statement that GitLab reads nothing from a copy made as it is no longer holds.

The version now appears in each place that gives the step:

• The CVE enrichment step in the gsutil download procedure.
• The sync cron example, which gains a 19.5 line to use after an upgrade.
• The file structure check, which gains the 19.5 path.

The notes use inline history text because they qualify steps inside existing topics.

The definition of done needs these docs in 19.5, so they cannot wait for the restructure in #627684 (closed). Its open drafts on this page change other lines and merge with this MR without conflict.

Related issues

Related to #561085.

Author's checklist

• Optional. Consider taking the GitLab Technical Writing Fundamentals course.
• Follow the:
  • Documentation process.
  • Documentation guidelines.
  • Style Guide.
• If you're adding a new page, add the product availability details under the H1 topic title.
• If you are a GitLab team member, request a review based on:
  • The documentation page's metadata.
  • The associated Technical Writer.

If you are a GitLab team member and only adding documentation, do not add any of the following labels:

• ~"frontend"
• ~"backend"
• ~"type::bug"
• ~"database"

These labels cause the MR to be added to code verification QA issues.

Reviewer's checklist

Documentation-related MRs should be reviewed by a Technical Writer for a non-blocking review, based on Documentation Guidelines and the Style Guide.

If you aren't sure which tech writer to ask, use roulette or ask in the #docs Slack channel.

• If the content requires it, ensure the information is reviewed by a subject matter expert.
• Technical writer review items:
  • Ensure docs metadata is present and up-to-date.
  • Ensure the appropriate labels are added to this MR.
  • Ensure a release milestone is set.
  • If relevant to this MR, ensure content topic type principles are in use, including:
    • The headings should be something you'd do a Google search for. Instead of Default behavior, say something like Default behavior when you close an issue.
    • The headings (other than the page title) should be active. Instead of Configuring GDK, say something like Configure GDK.
    • Any task steps should be written as a numbered list.
    • If the content still needs to be edited for topic types, you can create a follow-up issue with the docs-technical-debt label.
• Review by assigned maintainer, who can always request/require the reviews above. Maintainer's review can occur before or after a technical writer review.

This MR was written with AI assistance. Claude Code drafted the edit and checked each version claim against master and 19-4-stable-ee.