e2e: add testcases for backend-protocol annotations 

## Why do you need it?

annotations: 
+ `nginx.ingress.kubernetes.io/backend-protocol`


## How could it be?
Add testcases for backend-protocol annotations.

## Other related information
+ https://github.com/alibaba/higress/tree/main/test
+ https://github.com/alibaba/higress/issues/190