feat: Update Arbitrum block time to 250ms

[nimrod-teich]

Description

Closes: #XXXX

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Author Checklist

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please add links to any relevant follow up issues.

I have...

• read the contribution guide
• included the correct type prefix in the PR title, you can find examples of the prefixes below:
• confirmed ! in the type prefix if API or client breaking change
• targeted the main branch
• provided a link to the relevant issue or specification
• reviewed "Files changed" and left comments if necessary
• included the necessary unit and integration tests
• updated the relevant documentation or specification, including comments for documenting Go code
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Reviewers Checklist

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• confirmed the correct type prefix in the PR title
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• reviewed state machine logic, API design and naming, documentation is accurate, tests and test coverage

[github-actions]

Test Results

    6 files  ±0    129 suites  ±0   34m 38s ⏱️ +43s
2 995 tests ±0  2 986 ✅ +1  1 💤 ±0  3 ❌  - 1  5 🔥 ±0 
3 075 runs  ±0  3 066 ✅ +1  1 💤 ±0  3 ❌  - 1  5 🔥 ±0 

For more details on these failures and errors, see this check.

Results for commit 5b079f4. ± Comparison against base commit cf3ac0d.