fix(l1): wait before retring on error in dev's block producer

[ManuelBilbao]

Motivation

There was a race condition where dev's block producer starts before the RPC. In this scenario, the block producer tries to make some requests to the Engine API, failing three times in a row and thus ending.

Description

Add a small delay between retries so Engine RPC has time to get up

[github-actions]

Lines of code report

Total lines added: 5
Total lines removed: 0
Total lines changed: 5

Detailed view

+------------------------------------------------+-------+------+
| File                                           | Lines | Diff |
+------------------------------------------------+-------+------+
| ethrex/crates/blockchain/dev/block_producer.rs | 121   | +5   |
+------------------------------------------------+-------+------+

[Copilot]

Pull Request Overview

This PR fixes a race condition where the dev block producer starts before the Engine RPC server is ready, causing immediate failures when the producer attempts to make RPC calls.

Key Changes:

• Added a 300ms delay between retry attempts to allow the Engine RPC server time to initialize
• Sleep delays are consistently applied across all four error paths in the block production loop

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[Copilot]

The retry delay duration (300ms) is hardcoded as a magic number in multiple places. Consider extracting this to a named constant at the module or function level for better maintainability. For example:

const RETRY_DELAY_MS: u64 = 300;

Then use sleep(Duration::from_millis(RETRY_DELAY_MS)).await; throughout the function. This makes it easier to adjust the delay and ensures consistency across all retry points.

[avilagaston9]

+1