Dont send mentions to inbox of local community

also, dont start SendActivityTask for empty `to`, and remove
useless comment

lemmy_apub/src/activity_queue.rs

@@ -164,7 +164,7 @@ where
   Kind: Serialize,
   <T as Extends<Kind>>::Error: From<serde_json::Error> + Send + Sync + 'static,
 {
-  if !Settings::get().federation.enabled {
+  if !Settings::get().federation.enabled || to.is_empty() {
     return Ok(());
   }
 

lemmy_apub/src/comment.rs

@@ -506,7 +506,10 @@ async fn collect_non_local_mentions_and_addresses(
     }
   }
 
-  let mut inboxes = vec![community.get_shared_inbox_url()?];
+  let mut inboxes: Vec<Url> = vec![];
+  if !community.local {
+    inboxes.push(community.get_shared_inbox_url()?);
+  }
   inboxes.extend(mention_inboxes);
   inboxes = inboxes.into_iter().unique().collect();
 

lemmy_apub/src/fetcher.rs

@@ -55,9 +55,6 @@ where
 
   let timeout = Duration::from_secs(60);
 
-  // speed up tests
-  // before: 305s
-  // after: 240s
   let json = retry(|| {
     client
       .get(url.as_str())