Steps to reproduce

1. Install Ibexa DXP
2. Configure captcha to use ajax

form_builder: captcha: use_ajax: true  

1. Configure siteaccess match 

match: 
    Compound\LogicalAnd: 
        site: 
            matchers: 
                Map\Host: 
                    hostname: true
                Map\URI: 
                    site: true  

1. Create a Form with captcha
2. Go to hostname/site/forms/name_form
3. Check what link was used to generate the captcha

Result

To generate captacha we use URL /form/captcha/get-url/{id}. which in some cases may cause an error - for example, the main siteaccess requires login

Expected

We should include in URL siteaccess URI in this case: /site/form/captcha/get-url/{id} 

Note

Problem comes from ibexa/form-builder/src/bundle/Resources/public/js/fieldType/captcha.js. In this file we used hardcore URL: 

const request = new Request(`/form/captcha/get-url/${fieldId}`