MAGETWO-55397: [WCAG 2.0 AA] Fix Color and Contrast

- Remove redundant variable

Author: undefined-olha

lib/web/css/source/lib/variables/_colors.less

@@ -64,7 +64,6 @@
 @color-red10: #e02b27;
 @color-red11: #b30000;
 @color-red12: #d10029;
-@color-red13: #ee0000;
 
 @color-orange-red1: #ff5501;
 @color-orange-red2: #ff5601; // Legacy orange