slapos_slap_tool: No need revoke, only invalidate login is enough

See merge request !548
3 jobs for master in 0 seconds
Status Job ID Name Coverage
  External
failed SlapOS-Master.UnitTest-Master

01:56:25

failed SlapOS.Eggs.UnitTest-Master.Python2

00:15:47

failed SlapOS.Eggs.UnitTest-Master.Python3

00:16:24