calendar: set "proxy listbox ids" on some relation fields

to make it easier to find related documents
6 jobs for feat/relation_field_columns in 0 seconds
Status Job ID Name Coverage
  External
passed ERP5.CodingStyleTest-Master

00:55:06

failed ERP5.UnitTest-Master

01:29:38

failed ERP5.UnitTest-Zope2

03:41:29

passed SlapOS.Eggs.UnitTest-Master.Python2

00:13:28

passed SlapOS.Eggs.UnitTest-Master.Python3

00:14:35

passed Wendelin.UnitTest-Master

00:32:55