Replace GlDeprecatedButton with GlButton in approvers_list_item.vue

What does this MR do?

• Replace <gl-deprecated-button> with <gl-button> in ee/app/assets/javascripts/approvals/components/approvers_list_item.vue.
• Add the tooltip Remove.

Closes #219795 (closed)

Screenshots

Before

Note: This screenshot does not include a tooltip because the button did nor originally have one.

After

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

N/A

Security

N/A