Fix Saved Search failing to Clear "true" value on nuxeo-directory-suggestion tied to Boolean property

When having equipped a search form with a nuxeo-directory-suggestion tied to a Page Provider predicate for a Boolean schema property, the Clear button fails to reset the widget after creating a Saved Search using the "true" value.
 
Steps to reproduce:

1. Create a YesNo_Bool Vocabulary with these 2 entries :

   ID: true, label: Yes
   ID: false, label: No

1. Make a custom Document type with a Boolean field (in example jar attached, doctype is InvoiceTwo, and field is invoicetwo:discount)
2. In the document Create layout, have the Boolean field configurable with a checkbox element.
3. Make a custom Page Provider with a predicate on the Boolean field using the equals operator (in example, pp_InvoiceTwoSearch)
4. Add the Boolean field in the search form layout using a nuxeo-directory-suggestion element for the Boolean field.
5. Enable the search as a Drawer item accessible from the left-hand drawer.
6. Create two of these documents - one with Boolean field checked (to have value true), the other checked and then unchecked (value false).
7. Go to the search form (InvoiceTwo Search in the example) and select the "Yes" value from the widget.
8. Hit the search button - observe the document with value True is returned.
9. Save this search (with name "Yes Discount" for example).
10. Attempt to reset the search using the "CLEAR" button

Expected behavior: the nuxeo-directory-suggestion widget is cleared.

Actual Behavior: the nuxeo-directory-suggestion widget is not cleared ("Yes" is still present).

Note: this is not reproducible while populating the widget with No ("false"), as the Saved Search fails to save the value (see ELEMENTS-1585).

(see attached video - Studio project zips attached have set up doctype, search, and vocabulary needed to reproduce the issue)