Description of problem:
When testing OSP 17 with RHCS 5 we notice that collectd-ceph plugin was failing 

collectd.log
```
[2022-03-16 09:27:45] [warning] ceph plugin: cconn_handle_event(name=mon.controller-0,i=0,st=4): error 1
[2022-03-16 09:27:55] [error] ceph plugin: ds .targetBytes was not properly initialized.
[2022-03-16 09:27:55] [error] ceph plugin: JSON handler failed with status -1.
[2
```

After evaluating the perf counter schema we notice that instead proritycache key an empty string is returned.


[ceph: root@controller-0 /]# ceph daemon mon.controller-0 perf schema     
{
    "": {
        "target_bytes": {
            "type": 2,
            "metric_type": "gauge",
            "value_type": "integer",
            "description": "target process memory usage in bytes",
            "nick": "t",
            "priority": 8,
            "units": "bytes"
        },
        "mapped_bytes": {
            "type": 2,
            "metric_type": "gauge",
            "value_type": "integer",
            "description": "total bytes mapped by the process",
            "nick": "m",
            "priority": 8,
            "units": "bytes"
        },
        "unmapped_bytes": {
            "type": 2,
            "metric_type": "gauge",
            "value_type": "integer",
            "description": "unmapped bytes that the kernel has yet to reclaimed",
            "nick": "u",
            "priority": 8,
            "units": "bytes"
        },
        "heap_bytes": {
            "type": 2,
            "metric_type": "gauge",
            "value_type": "integer",
            "description": "aggregate bytes in use by the heap",
            "nick": "h",
            "priority": 8,
            "units": "bytes"
        },
        "cache_bytes": {
            "type": 2,
            "metric_type": "gauge",
            "value_type": "integer",
            "description": "current memory available for caches.",
            "nick": "c",
            "priority": 8,
            "units": "bytes"
        }
    },


Version-Release number of selected component (if applicable):
[ceph: root@controller-0 /]# ceph --version
ceph version 16.2.7-14.el8cp (1b7a9737ab205b421860c013d0ed4766b0bfe0da) pacific (stable)


How reproducible:
100%

Steps to Reproduce:
1. Deploy OSP 17 with RHCS 5


Actual results:
{
    "": {
        "target_bytes": {
            "type": 2,
            "metric_type": "gauge",
            "value_type": "integer",
            "description": "target process memory usage in bytes",
            "nick": "t",
            "priority": 8,
            "units": "bytes"
        },

Expected results:
{
    "prioritycache": {
        "target_bytes": {
            "type": 2,
            "metric_type": "gauge",
            "value_type": "integer",
            "description": "target process memory usage in bytes",
            "nick": "t",
            "priority": 8,
            "units": "bytes"
        },