debug: potential fix for unit test flake (microsoft#156177)

Fixes microsoft#155801

Author: connor4312

src/vs/workbench/contrib/debug/test/node/streamDebugAdapter.test.ts

@@ -49,7 +49,13 @@ suite('Debug - StreamDebugAdapter', () => {
 
 		const pipeName = crypto.randomBytes(10).toString('hex');
 		const pipePath = platform.isWindows ? join('\\\\.\\pipe\\', pipeName) : join(tmpdir(), pipeName);
-		const server = net.createServer(serverConnection).listen(pipePath);
+		const server = await new Promise<net.Server>((resolve, reject) => {
+			const server = net.createServer(serverConnection);
+			server.once('listening', () => resolve(server));
+			server.once('error', reject);
+			server.listen(pipePath);
+		});
+
 		const debugAdapter = new NamedPipeDebugAdapter({
 			type: 'pipeServer',
 			path: pipePath