fix: update modularUnit scenario to test response-side */* + bytes deserialization

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Co-authored-by: kazrael2119 <98569699+kazrael2119@users.noreply.github.com>

Author: Copilot

packages/typespec-ts/test/modularUnit/scenarios/operations/bodyParam/bytesWithWildcardContentType.md

@@ -1,21 +1,24 @@
-# bytes body with */* content type should be treated as binary
+# bytes response with */* content type should be treated as binary
 
-When an operation has `*/* ` content type and a `bytes` body, `isBinaryPayload` should return
-`true` so the parameter is typed as `Uint8Array` (binary) rather than `string` (base64).
+When a response has `*/*` content type and a `bytes` body, `isBinaryPayload` should return
+`true` so the response is deserialized as `Uint8Array` (binary) rather than `string` (base64).
 
 ## TypeSpec
 
 ```tsp
 @post op uploadFile(
+  @body body: string
+): {
   @header contentType: "*/*",
   @body body: bytes
-): void;
+};
 ```
 
 ## Operations
 
 ```ts operations
 import { TestingContext as Client } from "./index.js";
+import { getBinaryResponse } from "../static-helpers/serialization/get-binary-response.js";
 import { UploadFileOptionalParams } from "./options.js";
 import {
   StreamableMethod,
@@ -26,29 +29,35 @@ import {
 
 export function _uploadFileSend(
   context: Client,
-  body: Uint8Array,
+  body: string,
   options: UploadFileOptionalParams = { requestOptions: {} },
 ): StreamableMethod {
   return context
     .path("/")
-    .post({ ...operationOptionsToRequestParameters(options), contentType: "*/*", body: body });
+    .post({
+      ...operationOptionsToRequestParameters(options),
+      contentType: "text/plain",
+      headers: { accept: "*/*", ...options.requestOptions?.headers },
+      body: body,
+    });
 }
 
-export async function _uploadFileDeserialize(result: PathUncheckedResponse): Promise<void> {
-  const expectedStatuses = ["204"];
+export async function _uploadFileDeserialize(result: PathUncheckedResponse): Promise<Uint8Array> {
+  const expectedStatuses = ["200"];
   if (!expectedStatuses.includes(result.status)) {
     throw createRestError(result);
   }
 
-  return;
+  return result.body;
 }
 
 export async function uploadFile(
   context: Client,
-  body: Uint8Array,
+  body: string,
   options: UploadFileOptionalParams = { requestOptions: {} },
-): Promise<void> {
-  const result = await _uploadFileSend(context, body, options);
+): Promise<Uint8Array> {
+  const streamableMethod = _uploadFileSend(context, body, options);
+  const result = await getBinaryResponse(streamableMethod);
   return _uploadFileDeserialize(result);
 }
 ```