cmapi: cluster status does not show value for dbroots

Build tested: 1.5.4-1 (drone #598) cmapi (drone #253)

dbroots always show [] (empty).

On a 3-node cluster:

[centos7:root~]# curl -k -s https://s3pm1:8640/cmapi/0.4.0/cluster/status \
> --header 'Content-Type:application/json' \
> --header "x-api-key:$MCSAPIKEY" \
> | jq .
{
"timestamp": "2020-09-10 14:29:32.647142",
"s3pm1": {
"timestamp": "2020-09-10 14:29:32.653014",
"uptime": 3475,
"dbrm_mode": "master",
"cluster_mode": "readwrite",
"dbroots": [],
"module_id": 1,
"services": [

{ "name": "workernode", "pid": 17768 }

,

{ "name": "controllernode", "pid": 17826 }

,

{ "name": "PrimProc", "pid": 17837 }

,

{ "name": "ExeMgr", "pid": 17884 }

,

{ "name": "WriteEngine", "pid": 17892 }

,

{ "name": "DMLProc", "pid": 17929 }

,

{ "name": "DDLProc", "pid": 17930 }

]
},
"s3pm2": {
"timestamp": "2020-09-10 14:29:32.711391",
"uptime": 3630,
"dbrm_mode": "slave",
"cluster_mode": "readonly",
"dbroots": [],
"module_id": 2,
"services": [

{ "name": "workernode", "pid": 15218 }

,

{ "name": "PrimProc", "pid": 15226 }

,

{ "name": "ExeMgr", "pid": 15278 }

,

{ "name": "WriteEngine", "pid": 15286 }

]
},
"s3pm3": {
"timestamp": "2020-09-10 14:29:32.762429",
"uptime": 3782,
"dbrm_mode": "slave",
"cluster_mode": "readonly",
"dbroots": [],
"module_id": 3,
"services": [

{ "name": "workernode", "pid": 15797 }

,

{ "name": "PrimProc", "pid": 15806 }

,

{ "name": "ExeMgr", "pid": 15857 }

,

{ "name": "WriteEngine", "pid": 15866 }

]
},
"num_nodes": 3
}