[Vector Search] Can not access to PublicEndpoint by MatchService.

#### Environment details
* Ruby version: 3.2.2
* Rails version: 7.1.1
* Gem name and version: google-cloud-ai_platform-v1 (0.33.0)

### Steps to reproduce

1. Create index at Vector Search
2. Create index endpoint
3. Deploy index to index endpoint with public
4. Get public endpoint uri like ( `1111111111.asia-east1-833661946063.vdb.vertexai.goog` )
5. Access service to use Google::Cloud::AIPlatform::V1::MatchService::Client class
- `config.endpoint` : `1111111111.asia-east1-833661946063.vdb.vertexai.goog`
6. Use method `find_neighbors`
- `deployed_index_id`, `index_endpoint`, `queries`
7. `Google::Cloud::UnknownError (2:Stream removed. debug_error_string:{UNKNOWN:Error received from peer {grpc_message:"Stream removed", grpc_status:2, created_time:"2023-11-10T03:11:25.970084135+00:00"}}):`

### comment

I can find Deployed Index parameter is `public_access_enabled: false`.

But I create index by cURL command below.

```rb
curl -X POST \
-H "Content-Type: application/json" \
-H "Authorization: Bearer $(gcloud auth print-access-token)" \
"https://us-central1-aiplatform.googleapis.com/v1/projects/my-own-project-id/locations/us-central1/indexEndpoints" \
-d '{"display_name": "public-endpoint-name", "publicEndpointEnabled": true}' # it's true!
```

So it was created, but public_endpoint_enabled is false...

IndexEndpointService::Client got below.

A request was succeed by Postman to use gRPC request.

Do you know how to use public endpoint by gRPC access?

### Tries

- ✅ REST request by cURL
- ✅ gRPC request by Postman
- ❌ gRPC request by google-cloud-ai_platform-v1