tests/resource/aws_iam_user_login_profile: Ensure testDecryptPassword…

…AndTest honors current testing region (#15697)

Reference: #15688
Reference: #15690

Output from acceptance testing in AWS Commercial:

```
--- PASS: TestAccAWSUserLoginProfile_basic (25.86s)
```

Output from acceptance testing in AWS GovCloud (US):

```
--- PASS: TestAccAWSUserLoginProfile_basic (36.33s)
```

aws/resource_aws_iam_user_login_profile_test.go

@@ -253,7 +253,7 @@ func testDecryptPasswordAndTest(nProfile, nAccessKey, key string) resource.TestC
 		}
 
 		iamAsCreatedUserSession := session.New(&aws.Config{
-			Region:      aws.String("us-west-2"),
+			Region:      aws.String(testAccGetRegion()),
 			Credentials: credentials.NewStaticCredentials(accessKeyId, secretAccessKey, ""),
 		})
 		_, err = iamAsCreatedUserSession.Config.Credentials.Get()