Checkmk Werk 14561: Prometheus: allow operation of special agent without querying targets endpoint

ID: 14561 Title: Prometheus: allow operation of special agent without querying targets endpoint Component: Checks & agents Level: 1 Class: Bug fix Version: 2.2.0i1 Previously, the Prometheus special agent would query the endpoint `/api/v1/targets` regardless of what was configured in the Prometheus rule. This was an additional burden on users, which did not specify any scrape targets and therefore do not need this endpoint. E.g., it can lead to additional timeouts. With this werk, the endpoint `/api/v1/targets` is only queried if necessary.