Remove Serai from the ConfirmDkgTask

coordinator/substrate/src/set_keys.rs

@@ -39,6 +39,8 @@ impl<D: Db> ContinuallyRan for SetKeysTask<D> {
           continue;
         };
 
+        // This uses the latest finalized block, not the latest cosigned block, which should be
+        // fine as in the worst case, the only impact is no longer attempting TX publication
         let serai =
           self.serai.as_of_latest_finalized_block().await.map_err(|e| format!("{e:?}"))?;
         let serai = serai.validator_sets();