refactor(event cache): don't have find_event_with_relations return replies

It's unclear whether it's useful, especially in the case where it would
return an entire reply chain. It's not possible to filter in replies
only, using the function either, which is a sign that replies shouldn't
be indexed, IMO. In any case, that's something we can add back in the
future, if we want to.

crates/matrix-sdk/src/event_cache/room/mod.rs

@@ -1496,22 +1496,6 @@ mod tests {
         .await;
     }
 
-    #[async_test]
-    async fn test_event_with_reply_relation() {
-        let original_id = event_id!("$original");
-        let related_id = event_id!("$related");
-        let room_id = room_id!("!galette:saucisse.bzh");
-        let f = EventFactory::new().room(room_id).sender(user_id!("@ben:saucisse.bzh"));
-
-        assert_relations(
-            room_id,
-            f.text_msg("Original event").event_id(original_id).into(),
-            f.text_msg("A reply").reply_to(original_id).event_id(related_id).into(),
-            f,
-        )
-        .await;
-    }
-
     #[async_test]
     async fn test_event_with_thread_reply_relation() {
         let original_id = event_id!("$original");