Test badge counter fix

What does this MR do?

Since we started loading the test badge counter asyncronously, we missed an edge case where total_count === 0. The original function would return early if total_count was falsy, and since 0 is falsy we would never update the badge.

This MR changes this behaviour so we now show the 0 in the tab

Screenshots

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

Looking into this now, but it doesn;t seem like there's a spec for this file at all 🤔 If it's quick to add, I'll pop it in, otherwise I'll make a follow up to test this file.

• 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