the max value of 'max_request_bytes' is not match

We have a problem when load the file envoy.yaml to xds developing based on this project. The max value in envoy.yaml is 4294967295, but the max value in this project is 2147483647 (Java's Int type).

The content in envoy.yaml as follows:
```
http_filters:
- name: envoy.ext_authz
typed_config:
"@type": type.googleapis.com/envoy.extensions.filters.http.ext_authz.v3.ExtAuthz
http_service:
server_uri:
uri: 10.160.78.3:1001
cluster: ext-authz
timeout: 1s
failure_mode_allow: false
with_request_body:
max_request_bytes: **4294967295**
allow_partial_message: true
```

but when load the content to xds, the value exceeds the max value of Java's Int type.
---------
[api/src/main/proto/envoy/config/filter/http/ext_authz/v2/ext_authz.proto]
uint32 max_request_bytes ;

uint32 corresponds to int in Java and int32 in Go, so this will result in an error when load the envoy.yaml.

I

从 api/src/main/proto/envoy/config/filter/http/ext_authz/v2/ext_authz.proto 开始，跟踪其 uint32 max_request_bytes 值如何从 envoy.yaml 加载到 Java xDS 控制平面。使用 4294967295 重现报告的失败；当配置能够加载该值且不再出现当前的 Java Int-range 错误时，即表示完成。

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