Use empty query instead SELECT 1

What does this MR do?

Rails uses a SELECT 1 query to check the liveness of a database connection. From a client-side perspective, using an empty query ; instead increases throughput.

This change aims to replace the SELECT 1 query with the empty query ;.

See #292749 (closed).

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

We should test this on canary first.