Move handling of mp_num option

1 job for BMK-364 in 4 seconds (queued for 1 second)
Name Stage Failure
failed
job_test-parsers Test Parsers
  on default-runner-6fc894984d-hc5pt 1GnoT7cX
feature flags: FF_DISABLE_UMASK_FOR_DOCKER_EXECUTOR:true

Resolving secrets
Preparing the "docker" executor
Using Docker executor with image gitlab-registry.cern.ch/mschnepf/hep-workloads/hep-workload-builder:latest ...
Authenticating with credentials from job payload (GitLab Registry)

Pulling docker image gitlab-registry.cern.ch/mschnepf/hep-workloads/hep-workload-builder:latest ...

WARNING: Failed to pull image with policy "always": Error response from daemon: manifest for gitlab-registry.cern.ch/mschnepf/hep-workloads/hep-workload-builder:latest not found: manifest unknown: manifest unknown (manager.go:203:0s)
ERROR: Job failed: failed to pull image "gitlab-registry.cern.ch/mschnepf/hep-workloads/hep-workload-builder:latest" with specified policies [always]: Error response from daemon: manifest for gitlab-registry.cern.ch/mschnepf/hep-workloads/hep-workload-builder:latest not found: manifest unknown: manifest unknown (manager.go:203:0s)