CODER_NOTIFICATIONS_EMAIL_SMARTHOST's value is never used #15480
Description
CODER_NOTIFICATIONS_EMAIL_SMARTHOST is now deprecated, and superseded by CODER_EMAIL_SMARTHOST in #15270.
However, if CODER_EMAIL_SMARTHOST is unset then the value from CODER_NOTIFICATIONS_EMAIL_SMARTHOST should be used. Currently it is not, and I suspect it's because CODER_EMAIL_SMARTHOST has a default value:
emailSmarthost := serpent.Option{
Name: "Email: Smarthost",
Description: "The intermediary SMTP host through which emails are sent.",
Flag: "email-smarthost",
Env: "CODER_EMAIL_SMARTHOST",
Default: "localhost:587", // To pass validation.
Value: &c.Notifications.SMTP.Smarthost,
Group: &deploymentGroupEmail,
YAML: "smarthost",
}