Fix duplicate license header generations for snippets (#3106)

Co-authored-by: Qiaoqiao Zhang <55688292+qiaozha@users.noreply.github.com>

Author: kazrael2119

packages/autorest.typescript/src/generators/test/snippets.ts.hbs

@@ -1,6 +1,3 @@
-// Copyright (c) Microsoft Corporation.
-// Licensed under the MIT License.
-
 import { {{ clientClassName }} } from "../src/index.js";
 import { DefaultAzureCredential, InteractiveBrowserCredential } from "@azure/identity";
 import { setLogLevel } from "@azure/logger";

packages/rlc-common/src/test/template.ts

@@ -202,9 +202,6 @@ describe("My test", () => {
 `;
 
 export const snippetsContent = `
-// Copyright (c) Microsoft Corporation.
-// Licensed under the MIT License.
-
 {{#if isModularLibrary}}
 import { {{ clientClassName }} } from "../src/index.js";
 import { DefaultAzureCredential, InteractiveBrowserCredential } from "@azure/identity";