sap_general_preconfigure: Improve handling of the error message "No group server available" (lsr/sap-preconfigure issue #133)

[berndfinger]

This is a copy of linux-system-roles/sap-preconfigure#98, reported by alexxa:

... in task "ensure required package groups are installed". An OS command which perform this task and which will result in the same error message is "yum install @server" or "yum group install server".

[Wabri]

@berndfinger is this still a thing to solve?

[berndfinger]

Low demand, low urgency -> wontfix