[source-mongo] Connector stores the `_id` of deleted rows as a raw JSON object

### Connector Name

source-mongo

### Connector Version

1.5.17

### What step the error happened?

During the sync

### Relevant information

During CDC incremental syncs, the connector stores the `_id` of deleted rows as a raw JSON object:
```json
{
"_id": "{\"$binary\": {\"base64\": \"k7N/P5EMF4SZmAGW2Hx4sg==\",\"subType\": \"03\"}}",
"_ab_cdc_updated_at": "2025-05-22T17:19:42Z",
"_ab_cdc_cursor": 174793503000000271,
"_ab_cdc_deleted_at": "2025-05-22T17:19:42Z"
}
```

For rows that aren’t deleted, the `_id` field contains the expected Base64 string:
```json
{
"_id": "9gi3oVVEm42XxgGW9/YrGg==",
"Liked": true,
"Text": null,
"UpdatedAt": {
"DateTime": "2025-05-22T12:27:07.418Z",
"Ticks": 638835136274184098,
"Offset": 0
},
"_ab_cdc_updated_at": "2025-05-22T12:27:07Z",
"_ab_cdc_cursor": 174791722900000287,
"_ab_cdc_deleted_at": null
}
```

These examples come from destination-mssql v1.0.2, because I encountered issues with newest version of connector due to this behavior.

### Relevant log output

```shell

```

### Contribute

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