移除ddlApplicationRunner方法返回null (#5869)

spring-boot-starter/mybatis-plus-spring-boot-autoconfigure/src/main/java/com/baomidou/mybatisplus/autoconfigure/MybatisPlusAutoConfiguration.java

@@ -404,9 +404,6 @@ public class MybatisPlusAutoConfiguration implements InitializingBean {
     @Bean
     @ConditionalOnMissingBean
     public DdlApplicationRunner ddlApplicationRunner(@Autowired(required = false) List<IDdl> ddlList) {
-        if (ObjectUtils.isEmpty(ddlList)) {
-            return null;
-        }
         return new DdlApplicationRunner(ddlList);
     }
 }