Currently when one calls an operator with one the crd subcommands but no actual parameter the operator will just start.

We'd like to print the help message instead.

Currently
stackable-operator crd restart -> no help message, operator starts
stackable-operator crd restart -p -> CRD is printed, operator exists

Intended
stackable-operator crd restart -> help message is printed, operator exits
stackable-operator crd restart -p -> CRD is printed, operator exists