Fix full text input requiring Enter key press in Assets and Trash search

Steps to reproduce:

1. In vanilla Web UI, navigate to Assets Drawer Item.
2. Scroll down the search form and disable Auto-search
3. Input any value into the Full Text nuxeo-input at the top
4. Click the Search button at the bottom

Expected: Search is executed with contents of nuxeo-input for fulltext field applied

Actual: Search is executed without any input applied, resulting in default results. To have fulltext input applied, the Enter key must be hit prior to clicking the Search button.