[sample gen] Optional parameters are not being filtered out when generating sample code.

[v-jiaodi]

spec case:

• https://github.com/Azure/azure-rest-api-specs/tree/main/specification/applicationinsights/ApplicationInsights.LiveMetrics
• https://github.com/Azure/azure-rest-api-specs/tree/main/specification/ai/Face

ut :

## TypeSpec

```typespec
import "@typespec/http";
import "@typespec/rest";
import "@azure-tools/typespec-azure-core";
import "@azure-tools/typespec-client-generator-core";

using TypeSpec.Http;
using TypeSpec.Rest;
using Azure.Core;

@service(#{
  title: "Sample Service",
})
@server(
  "{endpoint}",
  "Sample endpoint",
  {
    @doc("The endpoint URL")
    endpoint: string = "https://example.com",
  }
)
namespace SampleService;

model Person {
  id: string;
  name: string;
}

@route("/persons")
interface Persons {
  @get
  list(
    @query start?: string,
    @query top?: int32,
  ): Person[];
}

Example

{
  "title": "List persons",
  "operationId": "Persons_List",
  "parameters": {
    "start": "00000000-0000-0000-0000-000000000000",
    "top": 20
  },
  "responses": {
    "200": {
      "body": [
        {
          "id": "person1",
          "name": "John Doe"
        }
      ]
    }
  }
}

Generated Sample

/** This file path is /samples-dev/listSample.ts */
import { SampleServiceClient } from "@azure/internal-test";

/**
 * This sample demonstrates how to execute list
 *
 * @summary execute list
 * x-ms-original-file: 2021-10-01-preview/json.json
 */
async function listPersons(): Promise<void> {
  const endpoint = process.env.SAMPLE_SERVICE_ENDPOINT || "";
  const client = new SampleServiceClient(endpoint);  // ❌ endpoint  should be optional as hasDefaultValue
  const result = await client.list({ start: "00000000-0000-0000-0000-000000000000", top: 20 });
  console.log(result);
}

async function main(): Promise<void> {
  await listPersons();
}

main().catch(console.error);