Sort metrics in metrics report MR widget

What does this MR do?

For #260388 (closed)

Sort the metrics in the metrics report MR widget in the following order:

1. changed: the metric has a different value in the head report compared to the base report (string compare)
2. new: the metric exists in the head report, but doesn't exist in the base report
3. removed: the metric exists in the base report, but doesn't exist in the head report
4. unchanged: the metric has the same value in the head report as it does in the base report

Note: I initially misinterpreted #260388 (closed) and made !54729 (merged), which separated changed and unchanged existing metrics, but didn't put them in the order described in the issue

Screenshots

	before	after !54729 (merged)	after this MR
order	new, existing, removed	new, changed existing, unchanged existing, removed	changed existing, new, removed, unchanged existing
screenshot

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

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done