fix(notifications): Remove generic admin email in favour of admins' email (#4519)

This removes the generic admin email setting.
Instead we use the email addresses set on the users' profile.
Allows for notifications to many recipients in case of multiple admins.
Email testing now sends the test email to the currently logged in user.

src/Ombi.Settings/Settings/Models/Notifications/EmailNotificationSettings.cs

@@ -10,7 +10,6 @@
         public string SenderAddress { get; set; }
         public string Username { get; set; }
         public bool Authentication { get; set; }
-        public string AdminEmail { get; set; }
         public bool DisableTLS { get; set; }
         public bool DisableCertificateChecking { get; set; }
     }