MAGETWO-90821: Upload button still get selected after cancel uploading an image

Set input visibility to hidden

Author: danmooney2

app/design/adminhtml/Magento/backend/web/css/source/components/_file-uploader.less

@@ -67,6 +67,7 @@
         overflow: hidden;
         position: absolute;
         width: 0;
+        visibility: hidden;
 
         &:focus {
             + .file-uploader-button {