fix(pinning): blank space between pinnedRight column and the last unpinned column

Change the order of conditionals to remove blank space between the last
unpinned column and the pinned right column in order to fix the
availableWidth behavior

This commit fixes #4949 (pull #6284)

Author: jpcleite

packages/core/src/js/factories/GridRenderContainer.js

@@ -601,14 +601,14 @@ angular.module('ui.grid')
       // Skip hidden columns
       if (!column.visible) { return; }
 
-      if (pinRightColumn) {
-        availableWidth += self.grid.scrollbarWidth;
-      }
-
       if (!pinRightColumn && column.colDef.pinnedRight) {
         pinRightColumn = true;
       }
 
+      if (pinRightColumn) {
+        availableWidth += self.grid.scrollbarWidth;
+      }
+
       if (angular.isNumber(column.width)) {
         // pixel width, set to this value
         if (column.colDef.allowFloatWidth) {