*: remove references to "slapgrid" in "This file is operated by slapgrid"

slapgrid is the old name of slapos node command.
2 jobs for failover-backend
Status Job ID Name Coverage
  External
failed SlapOS.SoftwareReleases.IntegrationTest-Master.Python2

failed SlapOS.SoftwareReleases.IntegrationTest-Master.Python3