Circuit breaker for API gateway | 熔断不生效

[ja-peng]

Issue Description

Type: bug report
依据wiki中api网关demo代码，编写了配置类，在spring启动的时候，自定义api分组加载到sentinel中，给api分组分配的流控规则可以生效，但是降级规则不能生效，在dashboard界面上的“请求链路”上加降级规则也不生效



jemeter测试结果：

Describe what you expected to happen

代码中加载的熔断降级规则生效

How to reproduce it (as minimally and precisely as possible)

Tell us your environment

    <dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
        <version>2.2.7.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>com.alibaba.csp</groupId>
        <artifactId>sentinel-transport-simple-http</artifactId>
        <version>1.8.1</version>
    </dependency>
    <dependency>
        <groupId>com.alibaba.csp</groupId>
        <artifactId>sentinel-spring-cloud-gateway-adapter</artifactId>
        <version>1.8.1</version>
    </dependency>
    <dependency>
        <groupId>com.alibaba.csp</groupId>
        <artifactId>sentinel-parameter-flow-control</artifactId>
        <version>1.8.1</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-gateway</artifactId>
    </dependency>

Anything else we need to know?