Products.ERP5Type.tests.ProcessingNodeTestCase: Make tic independent from the...

Products.ERP5Type.tests.ProcessingNodeTestCase: Make tic independent from the number of activities processed per tic.

That number was vastly decreased, causing tests to bail with "tic is
looping forever" for no good reason.
Convert such logic into a deadline one.
6 jobs for master
Status Job ID Name Coverage
  External
failed ERP5.CodingStyleTest-Master

01:09:48

failed ERP5.PerformanceTest-Master

00:27:34

running ERP5.UnitTest-Master

25990:59:07

failed ERP5.UnitTest-Master.Medusa

01:09:33

passed SlapOS.Eggs.UnitTest-Master.Python2

00:09:47

passed SlapOS.Eggs.UnitTest-Master.Python3

00:13:28