[Bugfix:Autograding] don't log "no available job" (#5460)
[Bugfix:Autograding] don't log "no available job" (#5460)


RCOS-Grading-Server/HWserver,RCOS-Grading-Server/HWserver,RCOS-Grading-Server/HWserver,RCOS-Grading-Server/HWserver,RCOS-Grading-Server/HWserver,Submitty/Submitty,RCOS-Grading-Server/HWserver,Submitty/Submitty,Submitty/Submitty,Submitty/Submitty,Submitty/Submitty,RCOS-Grading-Server/HWserver,Submitty/Submitty,Submitty/Submitty,Submitty/Submitty,Submitty/Submitty,RCOS-Grading-Server/HWserver,RCOS-Grading-Server/HWserver