Fix placeholder resizing in nuxeo-tag-suggestion

Steps to reproduce:

1. In Web UI with nuxeo-dam addon installed, create and open a Picture document.
2. Navigate to the right-hand side and click on the nuxeo-tag-suggestion underneath the "TAGS" label
3. Type in any amount of characters (without pressing enter key), then click off of the widget to cancel input

Expected: Full suggestion text (e.g. "Add tags to this document") is displayed

Actual: Suggestion text is truncated to "Add tags"; returns to normal after clicking on widget