Bug fix#17149 User Validation on Audit Repository .Save Method

[IbrahimMNada]

Description

If there's an existing issue for this PR then this fixes #17149

this pull request is a fix for this issue : #17149

Which states that a content publish can be established using ContentService with a non existing user.

A Simple Database Validation/ and simple caching mechanism were added in order to check if the user really exists in the database

[github-actions]

Hi there @IbrahimMNada, thank you for this contribution! 👍

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• It's clear what problem this is solving, there's a connected issue or a description of what the changes do and how to test them
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• Avoids creating breaking changes; note that behavioral changes might also be perceived as breaking
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If you realize that you might want to make some changes then you can do that by adding new commits to the branch you created for this work and pushing new commits. They should then automatically show up as updates to this pull request.

Thanks, from your friendly Umbraco GitHub bot 🤖 🙂

[JasonElkin]

Hey @IbrahimMNada, thanks for making a PR to fix this 🎉

Someone from the team will get this reviewed and get back to you soon.

[IbrahimMNada]

Any update on this
😅