What type of PR is this?

Fixes bug where default stream_idle_timeout in connection manager interferes with request timeouts set on HTTPRoute when set greater than 5 minutes preventing high request timeouts from being used without patching connection manager settings.

What this PR does:

If an HTTP request timeout is configured on the route and is non-zero, the idle_timeout will be set to the greater of 1hr or the configured request timeout. If the timeout on the HTTPRoute is set to 0 the idle_timeout is also set to 0 disabling both timeouts on the route.

How to reproduce:

1. Deploy demo into kind cluster and set a fault injection delay of 500s:

apiVersion: gateway.envoyproxy.io/v1alpha1
kind: BackendTrafficPolicy
metadata:
  name: fault-injection-delay
spec:
  targetRef:
    group: gateway.networking.k8s.io
    kind: HTTPRoute
    name: backend
  faultInjection:
    delay:
      fixedDelay: 500s

2. Configure timeout on HTTPRoute:

apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: backend
spec:
  hostnames:
  - www.example.com
  parentRefs:
  - group: gateway.networking.k8s.io
    kind: Gateway
    name: eg
  rules:
  - backendRefs:
    - kind: Service
      name: backend
      port: 3000
    matches:
    - path:
        type: PathPrefix
        value: /
    timeouts:
      request: 600s

3. Issue request via curl noting the 504 response code at the 5 minute mark

$ time curl -sv -H "Host: www.example.com" http://172.18.255.200/
*   Trying 172.18.255.200:80...
* Connected to 172.18.255.200 (172.18.255.200) port 80
> GET / HTTP/1.1
> Host: www.example.com
> User-Agent: curl/8.4.0
> Accept: */*
> 
< HTTP/1.1 504 Gateway Timeout
< content-length: 14
< content-type: text/plain
< date: Mon, 26 Feb 2024 18:20:32 GMT
< 
* Connection #0 to host 172.18.255.200 left intact
stream timeout
real	5m0.072s
user	0m0.017s
sys	0m0.023s

4. Note the reason for the early timeout in the request log:

"response_code":"504","response_flags":"DI,SI","response_code_details":"stream_idle_timeout"