fix: Make pre-messages w/o text want MDNs (#8004)

Maybe it's even good that MDNs will be sent for pre-messages only having placeholder text with the
viewtype and size, at least this way we notify the contact that we've noticed the message. Anyway,
with adding message previews the problem will be solved for the corresponding viewtypes.

src/message.rs

@@ -1879,9 +1879,10 @@ pub async fn markseen_msgs(context: &Context, msg_ids: Vec<MsgId>) -> Result<()>
             //
             // We also don't send read receipts for contact requests.
             // Read receipts will not be sent even after accepting the chat.
+            let wants_mdn = curr_param.get_bool(Param::WantsMdn).unwrap_or_default();
             let to_id = if curr_blocked == Blocked::Not
                 && !curr_hidden
-                && curr_param.get_bool(Param::WantsMdn).unwrap_or_default()
+                && wants_mdn
                 && curr_param.get_cmd() == SystemMessage::Unknown
                 && context.should_send_mdns().await?
             {
@@ -1903,6 +1904,11 @@ pub async fn markseen_msgs(context: &Context, msg_ids: Vec<MsgId>) -> Result<()>
                 None
             };
             if let Some(to_id) = to_id {
+                info!(
+                    context,
+                    "Queuing MDN to {to_id} for {id} from {curr_from_id}, wants_mdn={wants_mdn}, cmd={}.",
+                    curr_param.get_cmd()
+                );
                 context
                     .sql
                     .execute(