[Verification] Unclear verification by and login by in passwordless settings

## Background
- Environment: Staging
- Testing app: refuse-anchor-618, qademoappnative
- Demo apps (native): iOS 1.0(1692936706), android 1.0(1692847081)
- Device: iPhone X (iOS 16.0), pixel 5a (android 13), iPhone SE (iOS 16.4.1 (a))

## Description
Admin user has changed the login method - email verification to "Login Link", but after save and configure on the app again, it still shows 6-digit OTP when user sign up new account.

## Steps to reproduce
1. Select a project on Authgear portal
2. Go to Login Methods > Email > Passwordless > Verification
3. Select to Verify email by "Login Link"
4. Save
5. Configure the application on demo app
6. Click Authenticate to sign up
7. See that the next step is 6-digit OTP but not login link

## Expected result
Should change to use Login link for verification after user changed on portal.

## Screenshot

Demo app (after saving on portal and clicked "Configure" button again):

https://github.com/authgear/authgear-server/assets/12539486/1afe5044-a585-41e2-9b70-d1d44e017e28

Start by reproducing the passwordless verification flow in the staging project using the listed iOS and Android demo apps. Check the Login Methods > Email > Passwordless > Verification setting and the demo app's Configure step; done means selecting Login Link on the portal causes signup to proceed with a login link instead of a 6-digit OTP.

Written by the indexing model from the issue text.