ahas集成到zuul1.x网关限流后没有抛出ZuulException,导致无法进入Zuul的异常处理过滤器SendErrorFilter

## Issue Description

Type: *bug report*

### Describe what happened (or what feature you want)

ahas与zuul1.x集成实现网关限流。如果被限流，抛出BlockException之后，没有抛出ZuulException，因而无法进入Zuul的错误处理流程。
代码在：com.alibaba.csp.sentinel.adapter.gateway.zuul.filters.SentinelZuulPreFilter#run
95-103行
```java
} catch (BlockException var12) {
ZuulBlockFallbackProvider zuulBlockFallbackProvider = ZuulBlockFallbackManager.getFallbackProvider(fallBackRoute);
BlockResponse blockResponse = zuulBlockFallbackProvider.fallbackResponse(fallBackRoute, var12);
ctx.setRouteHost((URL)null);
ctx.set("serviceId", (Object)null);
ctx.setResponseBody(blockResponse.toString());
ctx.setResponseStatusCode(blockResponse.getCode());
ctx.getResponse().setContentType("application/json; charset=utf-8");
}

```

### Describe what you expected to happen
限流完成后抛出一个Zuul异常
```java
catch (BlockException e) {
ZuulBlockFallbackProvider zuulBlockFallbackProvider = ZuulBlockFallbackManager.getFallbackProvider(fallBackRoute);
BlockResponse blockResponse = zuulBlockFallbackProvider.fallbackResponse(fallBackRoute, var12);
ctx.setRouteHost((URL)null);
ctx.set("serviceId", (Object)null);
ctx.setResponseBody(blockResponse.toString());
ctx.setResponseStatusCode(blockResponse.getCode());
ctx.getResponse().setContentType("application/json; charset=utf-8");
throw new ZuulException(e,"sentinel流控",429,"SentinelZuulPreFilter");

```

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

1. 接入ahas（我接入的公网试用版本）
2. 在ahas网关防护中添加流控规则
3. 触发流控

### Tell us your environment
spring-cloud-zuul-starter-ahas-sentinel 1.2.2
spring-cloud-starter-netflix-zuul 2.2.6.RELEASE

### Anything else we need to know?

Start in SentinelZuulPreFilter#run around lines 95-103 and reproduce the rate-limiting flow with spring-cloud-zuul-starter-ahas-sentinel 1.2.2 and spring-cloud-starter-netflix-zuul 2.2.6.RELEASE. Confirm that a blocked request raises ZuulException and reaches Zuul's SendErrorFilter error handling path.

Written by the indexing model from the issue text.