VEX upload results in ISE 500 if it has invalid JSON

### Steps to Reproduce

Upload a VEX like this (notice the extra comma after analysis):
```
{
"bomFormat": "CycloneDX",
"specVersion": "1.5",
"version": 1,
"vulnerabilities": [
{
"id": "CVE-2017-18349",
"source": {
"name": "NVD"
},
"ratings": [
{
"severity": "high"
}
],
"analysis": {
"state": "not_affected",
"justification": "code_not_reachable"
},
}
]
}
```
You get ISE 500

### Expected Behavior

Return code is 400 and a proper validation message is returned

### Dependency-Track Version

4.13.1

### Dependency-Track Distribution

Container Image

### Database Server

PostgreSQL

### Database Server Version

_No response_

### Browser

N/A

### 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