fix(rlp): fix indexing in block rlp filenames

[danceratopz]

🗒️ Description

This PR fixes the indices used in the block RLP filenames (000n.rlp) that get created in the client container. n should start from 1 (block 1), not 0 (genesis).

This was an oversight in the initial rlp implementation and brings the *.rlp file naming inline with the Hive consensus simulator:

🔗 Related Issues

None.

✅ Checklist

• All: Set appropriate labels for the changes.
• All: Considered squashing commits to improve commit history.
• All: Added an entry to CHANGELOG.md. SKIP
• All: Considered updating the online docs in the ./docs/ directory.
• Tests: All converted JSON/YML tests from ethereum/tests have been added to converted-ethereum-tests.txt.
• Tests: Included the type and version of evm t8n tool used to locally execute test cases: e.g., ref with commit hash or geth 1.13.1-stable-3f40e65.
• Tests: Ran mkdocs serve locally and verified the auto-generated docs for new tests in the Test Case Reference are correctly formatted.