fix: use correct string for encryption info

encryption info needs a dedicated string for "Messages are end-to-end encrypted"
as the UI will add more infomation to the info messages,
smth. as "Tap for more information".

an alternative fix would have been to let the UI render the info-message
differently, but adding another string to core causes less friction.

src/contact.rs

@@ -1344,7 +1344,7 @@ WHERE addr=?
         let fingerprint_other = fingerprint_other.to_string();
 
         let stock_message = if contact.public_key(context).await?.is_some() {
-            stock_str::messages_e2e_encrypted(context).await
+            stock_str::messages_are_e2ee(context).await
         } else {
             stock_str::encr_none(context).await
         };