修复 last 方法的 condition 入参不生效的问题

mybatis-plus-core/src/main/java/com/baomidou/mybatisplus/core/conditions/AbstractWrapper.java

@@ -220,7 +220,9 @@ public abstract class AbstractWrapper<T, R, This extends AbstractWrapper<T, R, T
 
     @Override
     public This last(boolean condition, String lastSql) {
-        this.lastSql = StringPool.SPACE + lastSql;
+        if (condition) {
+            this.lastSql = StringPool.SPACE + lastSql;
+        }
         return typedThis;
     }