fix: send_msg_to_smtp: Return Ok if smtp row is deleted in parallel

Follow-up to ded8c02c0f. `smtp` rows may be deleted in parallel, in
this case there's just nothing to send.

src/chat.rs

@@ -4505,6 +4505,7 @@ pub(crate) async fn delete_and_reset_all_device_msgs(context: &Context) -> Resul
 /// Adds an informational message to chat.
 ///
 /// For example, it can be a message showing that a member was added to a group.
+/// Doesn't fail if the chat doesn't exist.
 #[allow(clippy::too_many_arguments)]
 pub(crate) async fn add_info_msg_with_cmd(
     context: &Context,