Fix full text input requiring Enter key press in Default search

After disabling auto search on nuxeo-default-search-form, the fulltext input is only applied when pressing the enter key - it should also be applied when clicking the Search button.

Steps to Reproduce:

1. Include the following in your custom *-bundle.html file to disable auto search on the Default search form:

   <!-- Disable auto on default search -->
   <nuxeo-slot-content name="defaultSearchMenuPage" slot="DRAWER_PAGES">
     <template>
       <nuxeo-search-form
         name="defaultSearch"
         search-name="default"
         provider="default_search"
         schemas="dublincore,common,file,uid"
       ></nuxeo-search-form>
     </template>
   </nuxeo-slot-content>

2. Navigate to Default search drawer button.
3. Fill the Full Text input widget with a value
4. Click the Search button without pressing the enter key beforehand

Expected result: fulltext input is applied and search returns corresponding results.

Actual result: fulltext input is not applied, search is executed with prior parameters.