Sort TestCase by status and execution_time

Ref: #228950 (closed)

What does this MR do?

This MR introduces the ability for a TestSuite object to sort our test_cases data by status and execution_time dsc.

It includes the following items:

• Adds sorted public method to our TestSuite object
• Sorts our data when rendering it to the frontend

Why are we doing this?

Part of effort to improve our Testing feature, we want to display the slowest tests at the top of our generated JUnit report.

This MR makes it possible to sort our data first by status then by execution_time

Screenshots

Before this MR	After this MR

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

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team