test: define SharedArrayBuffer as a known global

This commit defines SharedArrayBuffer as a global for all tests,
rather than adding comments to individual tests.

PR-URL: https://github.com/nodejs/node/pull/20849
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Yuta Hiroto <hello@hiroppy.me>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>

test/parallel/test-buffer-sharedarraybuffer.js

@@ -1,4 +1,3 @@
-/* global SharedArrayBuffer */
 'use strict';
 
 require('../common');