Fix default value of boolean field in multivalued complex property

How to reproduce:

• in Studio, create a new document type
• add a multivalued complex property and add a boolean property with a default value true in it (see https://connect.nuxeo.com/nuxeo/site/studio/ide?project=vdutat-sandbox-810-nuxeo&ticket=ST-2825-MRFxGeOxA2OUMLSeRQED-cas01.example.org#@feature:SUPNXP-21857.doc)
• deploy

Create a new instance of the new document type and add an element in the multivalued complex property, the box of the boolean property is not checked.