Add needs pipeline job limitation

What does this MR do and why?

This MR aims to provide more clarity on the needs:pipeline:job feature by explicitly specifying its limitation in multi-project pipelines. Additionally, it includes a link to the relevant feature request for adding support for this functionality.

Screenshots or screen recordings

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How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

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