test(credentials): do not modify developer $HOME aws#5791

## Problem
https://github.com/aws/aws-toolkit-vscode/blob/0164d4145e58ae036ddf3815455ea12a159d491d/packages/core/src/test/shared/credentials/userCredentialsUtils.test.ts#L38-L39

This test is deleting my actual aws config file.

## Solution
Update the environment variable to point to a fake location before test
Then recover them after test

Author: roger-zhangg

packages/core/src/test/shared/credentials/userCredentialsUtils.test.ts

@@ -18,31 +18,20 @@ import {
 import { UserCredentialsUtils } from '../../../shared/credentials/userCredentialsUtils'
 import { EnvironmentVariables } from '../../../shared/environmentVariables'
 import { makeTemporaryToolkitFolder } from '../../../shared/filesystemUtilities'
-import { getConfigFilename, getCredentialsFilename } from '../../../auth/credentials/sharedCredentialsFile'
 import { fs } from '../../../shared'
 
 describe('UserCredentialsUtils', function () {
     let tempFolder: string
-    let defaultConfigFileName: string
-    let defaultCredentialsFilename: string
 
-    before(async function () {
-        defaultConfigFileName = getConfigFilename()
-        defaultCredentialsFilename = getCredentialsFilename()
+    beforeEach(async function () {
         // Make a temp folder for all these tests
         // Stick some temp credentials files in there to load from
         tempFolder = await makeTemporaryToolkitFolder()
     })
 
     afterEach(async function () {
-        await fs.delete(defaultConfigFileName, { recursive: true })
-        await fs.delete(defaultCredentialsFilename, { recursive: true })
-
-        sinon.restore()
-    })
-
-    after(async function () {
         await fs.delete(tempFolder, { recursive: true })
+        sinon.restore()
     })
 
     describe('findExistingCredentialsFilenames', function () {

packages/toolkit/.changes/next-release/Bug Fix-a0acdaa1-7356-4f58-bc9b-fb7b708fe831.json

@@ -0,0 +1,4 @@
+{
+	"type": "Bug Fix",
+	"description": "Fix userCredentialsUtils.test.ts so it won't remove the actual aws config"
+}