MAGETWO-82809: [Backport 2.2-develop] Fix datetime type product that show current date when is empty in grids magento#11749

 - Merge Pull Request magento#11749 from enriquei4/magento2:DONT-SHOW-UNSETDATE
 - Merged commits:
   1. c93391f
   2. bb3fae9

Author: miguelbalparda

app/code/Magento/Ui/view/base/web/js/grid/columns/date.js

@@ -39,7 +39,7 @@ define([
         getLabel: function (value, format) {
             var date = moment(this._super());
 
-            date = date.isValid() ?
+            date = date.isValid() && value[this.index] ?
                 date.format(format || this.dateFormat) :
                 '';