grid: cleanup the duplicate supervisord processes

After 1.6.1 was deployed we have two processes, stop the redundant process.
3 jobs for master in 0 seconds
Status Job ID Name Coverage
  External
passed SlapOS-Master.UnitTest-Master

01:59:02

passed SlapOS.Eggs.UnitTest-Master.Python2

00:13:47

passed SlapOS.Eggs.UnitTest-Master.Python3

00:08:00