🐛 Source MongoDB v2: Failed to fetch schema MongoDB Atlas

## Environment
- **Airbyte version**: 0.33.4-alpha
- **OS Version / Instance**: Ubuntu 20.04 LTS on GCP
- **Deployment**: Docker
- **Source Connector and version**: airbyte/source-mongodb-v2:0.1.8
- **Destination Connector and version**: airbyte/destination-bigquery:0.5.0
- **Severity**: High
- **Step where error happened**: Setup new connection

## Current Behavior
I created source (MongoDB) and destination (BigQuery), checked connection - on this step all ok. After, i setup new connection, and started fetch data schema from mongo, this operation lasted about 30 min, and failed.


## Expected Behavior
Fetch data schema

## Logs
[error.txt](https://github.com/airbytehq/airbyte/files/7664159/error.txt)

LOG

```
2021-12-06 22:58:32 ERROR () LineGobbler(voidCall):82 - Exception in thread "main" com.mongodb.MongoCommandException: Command failed with error 16872 (Location16872): 'Invalid $project :: caused by :: '$' by itself is not a valid FieldPath' on server *******-shard-00-02.9lnlp.mongodb.net:27017. The full response is {"operationTime": {"$timestamp": {"t": 1638831510, "i": 4}}, "ok": 0.0, "errmsg": "Invalid $project :: caused by :: '$' by itself is not a valid FieldPath", "code": 16872, "codeName": "Location16872", "$clusterTime": {"clusterTime": {"$timestamp": {"t": 1638831510, "i": 4}}, "signature": {"hash": {"$binary": {"base64": "4swprwaSLZ01X1OdvfHQwUnrdy8=", "subType": "00"}}, "keyId": 6998221739326963718}}}
```

## Steps to Reproduce
1. Create source and destination
2. Check connection to source and destination
3. Setup new connection

## Are you willing to submit a PR?