Make remove user buttons consistent in admin and groups dashboards

What does this MR do and why?

It makes the delete user button consistent across admin and group management pages.

Screenshots

#	has visual changes?	path	before	after
1	✅	/groups/<group_id>/-/usage_quotas#seats-quota-tab
2	✅	/groups/<group_id>/-/group_members
3	✅	/admin/users
4	✅	/admin/users/<username>/projects
5	❌	/groups/<group_id>/-/group_members?tab=invited
6	❌	/groups/<group_id>/-/group_members?tab=groups
7	❌	/groups/<group_id>/-/group_members?tab=access_requests

How to set up and validate locally

1. Checkout the branch
2. As root visit /admin and observe the dropdown beside each user
3. From the previous step, click on one of the users then navigate to the "Groups and projects" tab and observe the delete button beside group(s) and project(s)
4. As a group owner, navigate to a group's members page (/groups/<group_id>/-/group_members) and observe the "Remove user" button
5. In a group with a paid plan, from the left sidebar select Settings > Usage Quotas, and observe the "Remove user" button

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 #329940 (closed)