Description of problem:
ceph mon stat --format json-pretty return output in plain format

Version-Release number of selected component (if applicable):
ceph version 14.2.11-181.el8cp 

How reproducible:
Always

Steps to Reproduce:
1. In 4.x cluster try to retrieve mon status in json-pretty format

Actual results:
[root@e22-h18-b04-fc640 ~]# sudo ceph mon stat --format json-pretty

e1: 3 mons at {e22-h14-b04-fc640=[v2:172.16.39.51:3300/0,v1:172.16.39.51:6789/0],e22-h18-b01-fc640=[v2:172.16.36.221:3300/0,v1:172.16.36.221:6789/0],e22-h18-b04-fc640=[v2:172.16.37.23:3300/0,v1:172.16.37.23:6789/0]}, election epoch 146, leader 0 e22-h18-b01-fc640, quorum 0,2 e22-h18-b01-fc640,e22-h14-b04-fc640


Expected results:
[ceph: root@magna008 /]# ceph mon stat --format json-pretty

{
    "epoch": 3,
    "min_mon_release_name": "pacific",
    "num_mons": 3,
    "leader": "magna008",
    "quorum": [
        {
            "rank": 0,
            "name": "magna008"
        },
        {
            "rank": 1,
            "name": "magna057"
        },
        {
            "rank": 2,
            "name": "magna110"
        }
    ]
}

Additional info:
(Already fixed upstream, Filed BZ to track verification in 4.3)