ref(less): Remove innerColumn (#39203)

static/less/shared-components.less

@@ -509,12 +509,6 @@ table.table.key-value {
   }
 }
 
-// Sparkline grid
-
-.innerColumn(@columnSpan: 1) {
-  width: ((@gridColumnWidth) * @columnSpan) + (@gridGutterWidth * (@columnSpan - 1)) - 10;
-}
-
 /**
 * Box
 * ============================================================================