[ccplugin] remove debug print

Besides from being a debug-only trace, it raises an error when
no actual document is indexed.

cubicweb_elasticsearch/ccplugin.py

@@ -89,7 +89,6 @@
                         raise_on_error=False,
                         raise_on_exception=False):
                     pass
-                print(_)
             else:
                 cnx.info(u'no elasticsearch configuration found, skipping')