Fix EMAIL_DEFAULT_FROM_ADDRESS was defined as non valid email at localhost

Fix EMAIL_DEFAULT_FROM_ADDRESS was defined based on BASE_URL and on localhost it resulted to `concrete5-noreply@localhost`

That may cause mail function to fail because SMTP server response: `504 Sender address rejected: need fully-qualified address`

Now at localhost or similar (has no suffix) it results to `concrete5-noreply@example.com` allowing emails to be sent