Allow for annotations on the scheduler pod for metrics collection

[dmildh-absci]

Hello. It would be nice if you could add an annotation to the scheduler pod so that you can configure metrics collection from Datadog. At the moment we have to patch the deployment with something like this. Thank you.

{
    "spec": {
      "template": {
        "metadata": {
          "annotations": {
            "ad.datadoghq.com/volcano-sh-scheduler.checks": "{\"openmetrics\": {\"init_config\": {}, \"instances\": [{\"openmetrics_endpoint\": \"http://%%host%%:8080/metrics\", \"namespace\": \"volcano-system\", \"metrics\": [\".*volcano_queue_.*\", \".*olcano_queue_.*\"]}]}}"
          }
        }
      }
    }
  }