Remove use strict directives in extension code

We compile with alwaysStrict so these directives are not needed

extensions/vscode-api-tests/src/utils.ts

@@ -3,8 +3,6 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
-'use strict';
-
 import * as vscode from 'vscode';
 import * as fs from 'fs';
 import * as os from 'os';