This should be moved into `OtterLimitsTestCase.setUp` unless it is being used else where.

Also, non-blocking: The fake_config could be initialized with a dictionary comprehension:
```
fake_config = {
    "limits": {
        "absolute": {key: number for key in ["maxGroups", "maxPoliciesPerGroup", "maxWebhooksPerPolicy"]}
    }
}
```