[aws-elasticache] - [Docs] - CfnReplicationGroup cluster mode is missing types

### Name of the resource

AWS::ElastiCache::ReplicationGroup

### Resource name

_No response_

### Reference Link

Original issue - https://github.com/aws/aws-cdk/issues/33365

### Details

The clusterMode property of the CfnReplicationGroup component should not be a plain string type, but 'enabled' | 'disabled' | undefined. The documentation (incorrectly?) lists the valid options for this property as Disabled or Enabled, with a capital D/E, which causes problems when you try to deploy, such as incorrectly triggering Cluster mode updates are not supported while attempting to update additional properties. If you instead change to lower-case typing in the CDK, it seems to work as expected. This is described in [this thread](https://repost.aws/questions/QUj6IF3l-qSsKKkD3yxY_EDw/elasticache-cluster-mode-updates-are-not-supported-while-attempting-to-update-additional-properties) as well.

So it seems that https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-elasticache-replicationgroup.html#cfn-elasticache-replicationgroup-clustermode is either incorrect or that the output produced by the CDK is different from its input (i.e. lowercase in CDK but titelcase in the API).

Either way, correctly typing this would avoid this issue entirely.