fix(cbridge): retain dr_sender if node out of sync

bridges/centralized-ethereum/src/actors/dr_sender.rs

@@ -171,7 +171,9 @@ impl DrSender {
                                 // Error sending transaction: node not synced, not enough balance, etc.
                                 // Do nothing, will retry later.
                                 log::error!("[{}] >< cannot broadcast dr_tx: {}", dr_id, e);
-                                continue;
+                                // In this case, refrain from trying to send remaining data requests, 
+                                // and let the dr_sender actor try again on next poll.
+                                return witnet_node_pkh;
                             }
                         }
                     }