`DocumentReference.create()` keeps trying to create an already existing document, leading to a hang in functions

### [READ] Step 1: Are you in the right place? ✅

### [REQUIRED] Step 2: Describe your environment

* Operating System version: `MacOS 14.5`
* Firebase Product: `functions`, `firestore`
* Node.js version: `v18.20.3`
* NPM version: `10.7.0`

### [REQUIRED] Step 3: Describe the problem

#### Steps to reproduce:
1. Create a new demo project via `firebase init`
2. Select `functions` and `firestore`
3. Run emulators through: `firebase emulators:start --inspect-functions --project demo-me`
4. Visit `http://127.0.0.1:5001/demo-me/us-central1/runMeTwice` in browser
5. Refresh

#### Relevant Code:
```json
{
"name": "functions",
"description": "Cloud Functions for Firebase",
"engines": {
"node": "18"
},
"main": "index.js",
"dependencies": {
"firebase-admin": "^12.1.0",
"firebase-functions": "^5.0.0"
},
"private": true
}
```

```js
//@ts-check
const { onRequest } = require("firebase-functions/v2/https");
const logger = require("firebase-functions/logger");
const { firestore, initializeApp } = require("firebase-admin");
const { initializeFirestore } = require("firebase-admin/firestore");

/** @type {firestore.Firestore} */
let _defaultFirestore;
function defaultFirestore() {
return _defaultFirestore ??= initializeFirestore(initializeApp(), {
preferRest: true,
})
}

exports.runMeTwice = onRequest(async (_, res) => {
try {
const doc = defaultFirestore().collection("test").doc("smt");
await doc.create({});
logger.log("Created");
} catch (error) {
logger.log(error);
} finally {
res.end();
}
});
```

### Expected behavior

The second time the function is ran, it should fail.

### Actual behavior

The first time the function is run the document is created. The second time, the function never completes.

Additionally, attaching to the node process, it seems the creation process keeps getting retried even though it should fail.