blessed-builds: report success although no artifacts are produced

@arno.bauernoppel one more thing i noticed with your current pipeline logic:

if a job does not produce any debs the pipeline is marked as succesfull although it stops, see:

http://localhost:8080/job/Builds/job/debs/job/deb-folks-amber-phone-staging-aarch64/

(folks sets export-dir so the debs end up somehwere else but the pipeline must never report success then).