slapos_jio: fix javascript syntax error

An error slipped in 92da569e (slapos_jio: Drop Handlebars, 2022-06-08)
8 jobs for master in 0 seconds
Status Job ID Name Coverage
  External
failed SlapOS-Master.UnitTest-Master

02:00:49

passed SlapOS.Eggs.UnitTest-Master.Python2

00:13:27

passed SlapOS.Eggs.UnitTest-Master.Python3

00:14:28

failed SlapOS-Master.UnitTest-Master

01:50:14

passed SlapOS.Eggs.UnitTest-Master.Python2

00:12:50

passed SlapOS.Eggs.UnitTest-Master.Python2

00:15:31

passed SlapOS.Eggs.UnitTest-Master.Python3

00:15:37

passed SlapOS.Eggs.UnitTest-Master.Python3

00:14:35