With help of User macro (Set with "no body")

## @param formName:title=Form name|type=string|required=true|desc=Name of the ConfiForms Form
## @param page:title=Page|type=confluence-content|required=false|desc=Page where the ConfiForms Form is configured

#set($labels = $content.getLabels())
#set($labelsList = "")
      
#foreach($label in $labels)
  #if ($labelsList != '') 
    #set($labelsList =  $labelsList + ",")
  #end
  #set($labelsList =  $labelsList + $label.name)
#end

 <ac:structured-macro ac:macro-id="45f61235-6d7c-4d90-b481-3d2db75be292" ac:name="confiform-entry-register" ac:schema-version="1">
      <ac:parameter ac:name="formName">$paramformName</ac:parameter>
<ac:parameter ac:name="pageTitle">$!{parampage}</ac:parameter>
      <ac:parameter ac:name="presetValues">textfield=$labelsList</ac:parameter>
      <ac:rich-text-body>
        <p>
          <br/>
        </p>
      </ac:rich-text-body>
    </ac:structured-macro>