test/integration/goDebug: fix the console log message

Currently it logs

`Setting up attach request for [object Object].`

Change-Id: I6abdec35fefe847234b7de1e48708ef8475f7c75
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/269138
Trust: Hyang-Ah Hana Kim <hyangah@gmail.com>
Reviewed-by: Suzy Mueller <suzmue@golang.org>

Author: hyangah

test/integration/goDebug.test.ts

@@ -357,7 +357,7 @@ suite('Go Debug Adapter', function () {
 		// an initialized event.
 		await Promise.all([
 			new Promise(async (resolve) => {
-				console.log(`Setting up attach request for ${debugConfig}.`);
+				console.log(`Setting up attach request for ${JSON.stringify(debugConfig)}.`);
 				const attachResult = await dc.attachRequest(debugConfig as DebugProtocol.AttachRequestArguments);
 				assert.ok(attachResult.success);
 				resolve();