Move Jira Connect user link to Vue

What does this MR do and why?

Related to #344887 (closed)

This MR relates to the Jira Connect App. In this MR we move the "user link" UI element from HAML to Vue.

Screenshots or screen recordings

Screenshots demonstrate no change to the user.

Signed in

Before	After

Signed out

Before	After

How to set up and validate locally

https://docs.gitlab.com/ee/development/integrations/jira_connect.html

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.