Question: Any reason ClientTrafficPolicy cannot be applied to multiple http (non https) listeners on the same port?

**Description**:
>Describe the issue.

We use `mergeGateways` setup with multiple `Gateway` objects.

Each Gateway listens on port HTTP 80, and has a different hostname.

We apply `ClientTrafficPolicy` to all Gateways using label selector to add `earlyRequestHeaders` for all requests.

Obviously when we try to do so, our ClientTrafficPolicy fails validation with this message:

```
ClientTrafficPolicy is being applied to multiple http (non https) listeners
(envoy-gateway-system/eg2/http-2) on the same port, which is not allowed
```

Is there any particular reson to not allow this? If not, then perhaps we can fix this in an upcoming release?

I see there was a PR [ #6279 fix: Allow Policy to attach to multiple http listeners](https://github.com/envoyproxy/gateway/pull/2967) but it clearly didn't apply to this scenario.

There is also a somewhat related discussion here: [Allow ClientTrafficPolicy to affect all listeners of a merged Gateway #3972](https://github.com/envoyproxy/gateway/issues/3972)