Remove unnecessary toLowercase when using CaseInsensitiveMap (#33336)

infra/rewrite/src/main/java/org/apache/shardingsphere/infra/rewrite/sql/token/common/pojo/generic/SubstitutableColumnNameToken.java

@@ -80,7 +80,7 @@ private Map<String, String> getLogicAndActualTables(final RouteUnit routeUnit) {
         }
         Map<String, String> result = new CaseInsensitiveMap<>();
         for (RouteMapper each : routeUnit.getTableMappers()) {
-            result.put(each.getLogicName().toLowerCase(), each.getActualName());
+            result.put(each.getLogicName(), each.getActualName());
         }
         return result;
     }