commands/create: Only add instruments/output processors once
commands/create: Only add instruments/output processors once

Ensure that instruments and output processors are only added to the
generated agenda once.

ARM-software/workload-automation,lisatn/workload-automation,lisatn/workload-automation,ARM-software/workload-automation,lisatn/workload-automation,setrofim/workload-automation,lisatn/workload-automation,setrofim/workload-automation,ARM-software/workload-automation,setrofim/workload-automation,ARM-software/workload-automation,setrofim/workload-automation