Don't set sortText

I might be reading this wrong, but it looks like we are setting it to
essentially arbitrary string at the moment, as there are no defined
order on the items in the *set* of completions.

crates/rust-analyzer/src/main_loop/handlers.rs

@@ -423,11 +423,8 @@ pub fn handle_completion(
     };
     let line_index = world.analysis().file_line_index(position.file_id)?;
     let line_endings = world.file_line_endings(position.file_id);
-    let mut count_sort_text_item = 0usize;
-    let items: Vec<CompletionItem> = items
-        .into_iter()
-        .map(|item| item.conv_with((&line_index, line_endings, &mut count_sort_text_item)))
-        .collect();
+    let items: Vec<CompletionItem> =
+        items.into_iter().map(|item| item.conv_with((&line_index, line_endings))).collect();
 
     Ok(Some(items.into()))
 }