[OTP] Resend cooldown should not be shared across interactions

Steps to reproduce

1. Sign in with a phone number
2. See the enter OTP page.
3. Click back
4. Sign in with the same phone number
5. See rate limit error

Expected

1. Sign in with a phone number
2. See the enter OTP page and receive a OTP
3. Click back
4. Sign in with the same phone number
5. See the enter OTP page and do not receive a new OTP code. The cooldown is resumed from Step 2.