add gitlab handle to team member modal

Why is this change being made?

This MR adds the team members GitLab handle to the member modal.

We're adding the handle because we should facilitate the communication with our Team members. On the Team page we have a GitLab tanuki that takes us to the user profile page, where finally we show the user's GitLab handle so we know how to communicate to this member. However, users can miss that the tanuki is clickable and not find the team members handle.

Additional Fix

This MR also adds a trailing slash to a link in handbook/acquisitions/index.html.md.erb that was causing the pipeline to fail intermittently.

Author Checklist

• Correct MR template applied (e.g blog post)
• Provided a concise title for the MR
• Added a description to this MR explaining the reasons for the proposed change, per say-why-not-just-what
• Assign this change to the correct DRI
  • If the DRI for the page/s being updated isn’t immediately clear, then assign it to your manager.
  • If your manager does not have merge rights, please ask someone to merge it AFTER it has been approved by your manager in #mr-buddies.
  • If the changes relate to any part of the project other than updates to content and/or data files please make sure to ping @gl-static-site-editor in a comment for a review and merge. For example changes to .gitlab-ci.yml, JavaScript/CSS/Ruby code or the layout files.

For help with failing pipelines reach out in #mr-buddies in Slack

Closes #8137 (closed)