[2.3.0] Checkmk Werk 16176 created: postfix: Fix Postfix status monitoring for agents run in Docker

[//]: # (werk v2) # postfix: Fix Postfix status monitoring for agents run in Docker key | value ---------- | --- compatible | yes version | 2.3.0b4 date | 2024-03-13T09:57:01+00:00 level | 1 class | fix component | checks edition | cre Previously, Checkmk agent used the data from /proc to determine if Postfix instance is running. Since docker containers don't have permissions to read /proc, the agent always reported the Postfix instance as 'not running'. This resulted in CRIT 'Postfix status' service even if Postfix instance was running correctly.