Convert single tab partial to Pajamas

What does this MR do and why?

This MR converts HAML tabs present in app/views/devise/shared/_tab_single.html.haml to use gl_tabs_nav helper that uses Pajamas Design System.

Screenshots or screen recordings

It is a shared partial, hence screenshots not applicable.

How to set up and validate locally

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

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 #230793 (closed)