Replace issues time tracking progress bar with gitlab-ui's progress bar

What does this MR do?

Replace issues time tracking progress bar with gitlab-ui's progress bar

Are there points in the code the reviewer needs to double check?

I've set the height for the progress bar to be 6px to be consistent with our other progress bars (eg. milestones page). Previously the progress bar for time tracking was using 5px. Need to check if we are okay with 6px for the progress bar in all cases.

Why was this MR needed?

First reusable component :)

Screenshots (if relevant)

Before	After

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Conform by the code review guidelines
  • Has been reviewed by a UX Designer
  • Has been reviewed by a Frontend maintainer
  • Has been reviewed by a Backend maintainer
  • Has been reviewed by a Database specialist
• Conform by the merge request performance guides
• Conform by the style guides
• Conform by the database guides
• If you have multiple commits, please combine them into a few logically organized commits by squashing them
• Internationalization required/considered
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

Closes gitlab-ui#11 (closed)