rule checker consumes too much cpu in big cluster

[lhy1024]

Enhancement Task

In some big clusters, rule-checker consumes too much cpu

cluster1:

cluster2:

There are 107 stores and 180w regions in cluster2, and simple rules.

[
  {
    "group_id": "pd",
    "id": "dc1-f",
    "start_key": "",
    "end_key": "",
    "role": "follower",
    "is_witness": false,
    "count": 2,
    "label_constraints": [
      {
        "key": "dc",
        "op": "in",
        "values": [
          "dc1"
        ]
      }
    ],
    "location_labels": [
      "dc",
      "host"
    ],
    "create_timestamp": 1736992391
  },
  {
    "group_id": "pd",
    "id": "dc1-l",
    "start_key": "",
    "end_key": "",
    "role": "learner",
    "is_witness": false,
    "count": 1,
    "label_constraints": [
      {
        "key": "dc",
        "op": "in",
        "values": [
          "dc1"
        ]
      }
    ],
    "location_labels": [
      "dc",
      "host"
    ],
    "create_timestamp": 1736992391
  },
  {
    "group_id": "pd",
    "id": "dc2",
    "start_key": "",
    "end_key": "",
    "role": "voter",
    "is_witness": false,
    "count": 3,
    "label_constraints": [
      {
        "key": "dc",
        "op": "in",
        "values": [
          "dc2"
        ]
      }
    ],
    "location_labels": [
      "dc",
      "host"
    ],
    "create_timestamp": 1736992391
  }
]