Re-enable the #6281 test on cppia (#6303)

see HaxeFoundation/hxcpp@5d16835

tests/unit/src/unit/issues/Issue6281.hx

@@ -8,8 +8,6 @@ class Issue6281 extends unit.Test {
     }
 
     public function test() {
-        #if !cppia
         eq('foo', check);
-        #end
     }
-}
+}