Using uuid as a key results in kafka message with quotes at beginning and end

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct

### On what operating system are you seeing the problem?

_No response_

### VS Code version

Version: 1.110.0 (Universal)
Commit: 0870c2a0c7c0564e7631bfed2675573a94ba4455
Date: 2026-03-04T01:20:28.863Z (5 days ago)
Electron: 39.6.0
ElectronBuildId: 13330601
Chromium: 142.0.7444.265
Node.js: 22.22.0
V8: 14.2.231.22-electron.0
OS: Darwin arm64 25.3.0

### Version of Confluent extension

2.2.2

### To Reproduce

1. Define an avro value schema that allows the message from step 2 (!! No Key schema defined!)
2. Create a json file that contains this data:
```json
{
"key": "663004D4-CE76-484F-9ADD-9A4B7D0EEEF4",
"value": {
"randomValue": "randomKey"
}
}
```
3. Publish the message via the plugin

### Current vs. Expected behavior

**Current:**

When I check now in AKHQ how the message was produced, I see the following:

**Expected:**

I only expect to see the UUID without any quotes.

### Relevant log output

```shell

```

### Which area(s) are affected? (Select all that apply)

Messages

### Additional context

_No response_