erp5_xhtml_style: do not index xhtml style by default

See merge request !1504
15 jobs for master in 0 seconds
Status Job ID Name Coverage
  External
failed ERP5.CodingStyleTest-Master

04:05:37

failed ERP5.UnitTest-Master

02:19:03

failed ERP5.UnitTest-Master.Medusa

03:34:40

passed SlapOS.Eggs.UnitTest-Master.Python2

00:10:13

passed SlapOS.Eggs.UnitTest-Master.Python3

00:12:21

passed ERP5.CodingStyleTest-Master

01:32:43

failed ERP5.UnitTest-Master

01:23:27

failed ERP5.UnitTest-Master

05:28:04

failed ERP5.UnitTest-Master.Medusa

03:56:26

passed SlapOS.Eggs.UnitTest-Master.Python2

00:19:26

passed SlapOS.Eggs.UnitTest-Master.Python2

00:21:40

passed SlapOS.Eggs.UnitTest-Master.Python2

00:10:28

passed SlapOS.Eggs.UnitTest-Master.Python3

00:34:03

passed SlapOS.Eggs.UnitTest-Master.Python3

00:12:27

passed SlapOS.Eggs.UnitTest-Master.Python3

00:13:48