Vulnerability Audit: sorting on CVSS score shows - (dash) on top

### Current Behavior

In the Vulnerability Audit screen, sorting on CVSS scores shows the - before an actual score

### Steps to Reproduce

1.have a project that has vulnerabilities that have CVSS scores and some that do not
2.Open Vulnerability Audit
3. sort on CVSSv3
4. see the sorting puts the vulnerabilities without a score above the ones with a score

### Expected Behavior

Sorting from High -> low should show the ones with the highest scores first, - at the bottom
Sorting from Low -> high should show the ones with - first, then the ones with the lowest scores.

### Dependency-Track Version

4.12.2

### Dependency-Track Distribution

Container Image

### Database Server

PostgreSQL

### Database Server Version

_No response_

### Browser

Google Chrome

### Checklist

- [x] I have read and understand the [contributing guidelines](https://github.com/DependencyTrack/dependency-track/blob/master/CONTRIBUTING.md#filing-issues)
- [x] I have checked the [existing issues](https://github.com/DependencyTrack/dependency-track/issues) for whether this defect was already reported