test(amazonq): test failure supplementalContext.test.ts #6021

## Problem
same issue #6019 is trying to fix
misuse of `sinon.alwaysReturned()`

## Solution
`sinon.returns()`

Author: Will-ShaoHua

packages/amazonq/test/unit/codewhisperer/util/supplemetalContextUtil.test.ts

@@ -21,7 +21,7 @@ describe('supplementalContextUtil', function () {
 
     beforeEach(async function () {
         testFolder = await TestFolder.create()
-        sinon.stub(FeatureConfigProvider.instance, 'getProjectContextGroup').alwaysReturned('control')
+        sinon.stub(FeatureConfigProvider.instance, 'getProjectContextGroup').returns('control')
     })
 
     afterEach(function () {