Phone number is treated as email (`<number>@sms.cal.com`) when only Phone Number field is enabled in Booking Questions

[Golu07-max]

When an event type is configured to collect only a phone number (with no email field enabled), the entered phone number is being automatically converted into an email-like value in Bookings Tab, in Reply-To field of the confirmation email, in response section of API.

Specifically, the phone number is appended with @sms.cal.com and shown as the user's email.

Example:
If a user enters XXXXXXXXXX as their phone number while booking, it appears as:
XXXXXXXXXX@sms.cal.com

Steps to Reproduce

1. Create or edit an Event Type
2. Go to Booking Questions
3. Enable Phone Number field
4. Disable Email field (so only phone number is collected)
5. Book the event as an invitee
6. Enter a phone number (e.g. 9999999999)
7. Complete the booking