agent2: Port retry logic (#36421)

Release Notes:

- N/A

crates/agent_ui/src/agent_diff.rs

@@ -1523,6 +1523,7 @@ impl AgentDiff {
             AcpThreadEvent::EntriesRemoved(_)
             | AcpThreadEvent::Stopped
             | AcpThreadEvent::ToolAuthorizationRequired
+            | AcpThreadEvent::Retry(_)
             | AcpThreadEvent::Error
             | AcpThreadEvent::ServerExited(_) => {}
         }