software/erp5/test: drop workaround for old slapos.cookbook

Since 2de4c80f generic_mysql does not
sleep so long between retries
3 jobs for 1.0
Status Job ID Name Coverage
  External
failed SlapOS.SlapRunner.ResilienceTest-Master.ERP5

failed SlapOS.SoftwareReleases.IntegrationTest-Master.Python2

failed SlapOS.SoftwareReleases.IntegrationTest-Master.Python3