[Phone-login] Deleted-email email message could use a bit of improvement

[seav]

Steps to reproduce the error

1. With an account that has a verified email address and phone number, update the profile to delete the email address.
2. Check the email account corresponding to the deleted email address.

Actual behavior

We get the following terse email message:

Subject: Deleted email at Cadasta Platform

Removed email address <email-address>.

Expected behavior

The message could use some improvement. Something like the following:

You are receiving this email because a user at Cadasta Platform removed the email address for the account linked to this email address.

If it wasn't you who removed the email address, please contact us immediately at security@cadasta.org.

The Cadasta Team.

[seav]

I think this bug is no longer an issue ever since we restricted user accounts from having both a verified email address and a verified phone number.