[v4][v5][v6] Update the default copyright text

[ramya-rao-a]

From Azure/azure-sdk-for-js#3837, lets update the MICROSOFT_MIT_NO_VERSION to produce

/*
 * Copyright (c) Microsoft Corporation.
 * Licensed under the MIT License.
 *
 * Code generated by Microsoft (R) AutoRest Code Generator.
 * Changes may cause incorrect behavior and will be lost if the code is
 * regenerated.
 */

instead of

/*
 * Copyright (c) Microsoft Corporation. All rights reserved.
 * Licensed under the MIT License. See License.txt in the project root for
 * license information.
 *
 * Code generated by Microsoft (R) AutoRest Code Generator.
 * Changes may cause incorrect behavior and will be lost if the code is
 * regenerated.
 */

[joheredi]

This has been fixed in autorest.common