Fix the intermittent error in node initialization

It sometimes fails with
```
thread 'track_blocks' panicked at 'called `Result::unwrap()` on an `Err` value: Connect(Io(Os { code: 111, kind: ConnectionRefused, message: "Connection refused" }))', /home/junha/Projects/foundry/integration-test/src/lib.rs:147:47
```

Start by inspecting integration-test/src/lib.rs around line 147 and the track_blocks thread to understand how node initialization establishes its connection. Reproduce the intermittent ConnectionRefused failure, then verify that the integration test no longer panics during initialization and that the relevant node-tracking flow completes reliably.

Written by the indexing model from the issue text.