Property (clusterType) in managedCassandra.json API Spec

In the portal, there is the ability to change a managed cassandra cluster b/w Production and NonProduction, this appears to be done by calling https://management.azure.com/subscriptions/subscriptions//resourceGroups//providers/Microsoft.DocumentDB/cassandraClusters/?api-version=2021-10-15

Where the body of the request is:
```
{
"location": "Australia East",
"properties": {
"delegatedManagementSubnetId": "/subscriptions//resourceGroups//providers/Microsoft.Network/virtualNetworks//subnets/",
"clusterType": "Production"
}
}
```
However, the property is not present in https://github.com/Azure/azure-rest-api-specs/blob/main/specification/cosmos-db/resource-manager/Microsoft.DocumentDB/stable/2021-10-15/managedCassandra.json

What does this property do?

Start with specification/cosmos-db/resource-manager/Microsoft.DocumentDB/stable/2021-10-15/managedCassandra.json and compare it with the managed Cassandra request shown in the issue. Trace the 2021-10-15 API operation and determine whether clusterType belongs in the specification and what its documented behavior should be. Done means the property’s status and behavior are resolved in the spec or issue discussion.

Written by the indexing model from the issue text.