routePrefix option in host.json

I added `routePrefix` option to host.json to use custom route and domain.
For example, if custom domain is `webapp.com`, I want to call API with `/azure/api` route.

It worked in the local environment, but on GitHub action process, got below error.
```
---End of Oryx build logs---
Function Runtime Information. OS: Linux, Functions Runtime: v3, Node version: 12.X
Finished building function app with Oryx
Found and validated 'routes.json' within build artifacts folder.
Error in processing api build artifacts: the host.json file cannot specify a http.routePrefix value other than 'api'.
```

My host.json settings:
```
{
"version": "2.0",
"watchDirectories": [ "lib" ],
"extensions": {
"http": {
"routePrefix": "azure/api",
}
},
"extensionBundle": {
"id": "Microsoft.Azure.Functions.ExtensionBundle",
"version": "[1.*, 2.0.0)"
}
}

```

Is the routePrefix option is not supported in the azure static web app?