Use the GlNewDropdown in metrics dashboard

What does this MR do?

This swaps the usage of GlDropdown to GlNewDropdown restoring the missing check mark icons in the process as well as dealing with some future technical debt

issue: #210514 (closed)

Screenshots

Before	After

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides