Rename remove user button in project members

What does this MR do and why?

This MR fixes #354332 (closed) The following changes are made:

• Rename label of Remove user button to Remove member to align better with the wording of the rest of the page
• Remove tooltip which is not needed anymore

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Go to a project > members
2. Locate the Remove member 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.

Closes #354332 (closed)