Add comment and spec to explain single request

What does this MR do and why?

In this MR, an explanation is added to clarify the need to mark the query as a single request. As well, a test is included to ensure this option exists.

Screenshots or screen recordings

There is no UI/UX change in this MR

How to set up and validate locally

Not applicable

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #372527 (closed)