Gen2: Encoding issue with special characters in path parameters

### Version info

**node:** v18.16.0
**firebase-functions:** v4.4.1
**firebase-tools:** v12.5.2
**firebase-admin:** v11.8.0

### Steps to reproduce
**This issue was not encountered in gen1, and special characters in path parameters were correctly encoded.**

- Deploy a Firebase Cloud Function Gen2 using a Firestore trigger as follows:
```javascript
import { log } from "firebase-functions/logger";
import { onDocumentUpdated } from "firebase-functions/v2/firestore";

export const testPlanet = onDocumentUpdated("planetes/{planeteId}", async (event) => {
log(event.params.planeteId);
});
```
- Ensure that the `planeteId` document contains special characters such as "é", "è", "à", etc. Example: "Helvétios", "Électre".
- Observe the `planeteId` value in the deployed function

### Expected behavior

The `planeteId` value should be correctly encoded and displayed in UTF-8, preserving special characters such as "é", "è", "à", etc., in the deployed Firebase Cloud Function Gen2.

### Actual behavior

After deploying the Firebase Cloud Function Gen2, the `planeteId` value appears to be incorrectly encoded, resulting in a value like `Helvétios` becoming `Helvétios` or `Électre` becoming `Électre`.

### Were you able to successfully deploy your functions?

Yes, the deployment was successful without any error messages.