Revert "check_mailq: add $mailq to check output, so it is easily visible what was autodetected"

This reverts commit 21750b173b8d98eaddcf99b7372236a2df2eb4c4.
Revert "check_mailq: document autodetection in the usage output"

This reverts commit 8e087cf4a6f741e35649d5df3e9b3a57615ff0a9.
Revert "check_mailq: try to autodetect which mailq implementation we are using"

This reverts commit bc4113fba2d251b70f8d9dae80f1b18033cace40.