The response of :9102/stats with or without instance id filter has duplicate entries for "key_size_distribution". It is not prefixed with <bucketName>:<scope>:<collection>:<indexName>

Reproduction Steps:

1. Create a single node cluster with kv, index and query services.
2. Create some indexes (at least 2)
3. curl -X GET -u Administrator:password http://<ip>:9102/stats or curl -X GET -u Administrator:password http://<ip>:9102/stats -d ' {"instances": [<instance_id>]}'