axoverlay: Update to dynamic user

[pataxis]

Describe your changes

Update axoverlay example to use dynamic user.

Checklist before requesting a review

• [x] I have performed a self-review of my own code
• [x] I have verified that the code builds perfectly fine on my local system
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] I have verified that my code follows the style already available in the repository
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation