web_renderjs_ui_test: adjust testPrintActions

Since 05210e87 (erp5_web_renderjs_ui: add LabelField support,
2020-05-26) we have label field support, so this labelfield is no longer
rendered with the fallback "read only field" gadget and markup is
different. Update selector to make the test happy.
9 jobs for master in 0 seconds
Status Job ID Name Coverage
  External
passed ERP5.CodingStyleTest-Master

00:49:37

passed ERP5.PerformanceTest-Master

00:32:54

failed ERP5.UnitTest-Master

01:31:37

passed SlapOS.Eggs.UnitTest-Master.Python2

00:28:05

passed SlapOS.Eggs.UnitTest-Master.Python3

01:09:23

passed SlapOS.Eggs.UnitTest-Master.Python2

00:25:50

passed SlapOS.Eggs.UnitTest-Master.Python2

00:21:45

passed SlapOS.Eggs.UnitTest-Master.Python3

00:29:54

passed SlapOS.Eggs.UnitTest-Master.Python3

00:26:14