test: increase timeout for extension tests

The Workspace Symbols test has been timing out in the long test. The
case where the GOROOT is scanned for symbols as well takes about
15000 on the long tests. Increasing the timeout should make this test
succeed more.

Updates golang/vscode-go#832

Change-Id: I3bf0f4ccc1b74c1b9e1aa1bca32d8f90f01b2e96
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/277192
Trust: Suzy Mueller <suzmue@golang.org>
Run-TryBot: Suzy Mueller <suzmue@golang.org>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
diff --git a/test/integration/extension.test.ts b/test/integration/extension.test.ts
index 66dd9c3..3957b2e 100644
--- a/test/integration/extension.test.ts
+++ b/test/integration/extension.test.ts
@@ -42,7 +42,7 @@
 } from '../../src/util';
 
 suite('Go Extension Tests', function () {
-	this.timeout(15000);
+	this.timeout(20000);
 
 	const dummyCancellationSource = new vscode.CancellationTokenSource();