Werk #15850: Agent plugin for monitoring Mailman 3 mailing lists

Before this werk, Checkmk included the agent plugin mailman_lists, which monitored Mailman 2 mailing lists. As of this werk, Checkmk includes the plugins mailman2_lists and mailman3_lists, which monitor Mailman 2/3 mailing lists. If the bakery is configured to deploy the Mailman plugin, both plugins will be installed, since only one of them will be operational, depending on the Mailman version installed on the target system.

To the list of all Werks