Geo: Fix single-file snippets for Geo secondaries

What does this MR do?

Geo mostly supported snippets, until !43246 (merged) was released.

This MR adds back just enough code to ensure existing single-file snippets functionality isn't lost on Geo secondaries. The quarantined QA spec will be dequarantined in a separate MR !44647 (closed).

Note that &2809 (closed) will soon be released (probably 13.6) which will add complete Geo replication for snippets including multiple-file snippets.

Related to: #262103 (closed)

Screenshots

Before	After

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry Note about the Danger warning: While the changelog indicates that this change fixes EE, I feel strongly that the code changes are safest in their original locations.
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.