feat: set HPP fast withdrawal time to 24 hours

[findmytrueself]

Configure fastWithdrawalTime (86400000 ms) for HPP Mainnet and HPP Sepolia to match the announced fast withdrawal window.

Summary

HPP announced that Arbitrum fast withdrawal is enabled with a 7 day → 24 hour user-facing confirmation window. The bridge UI uses bridgeUiConfig.fastWithdrawalTime (milliseconds) in getBridgeUiConfigForChain / getConfirmationTime to treat fast withdrawal as active and to drive withdrawal ETA strings, approximate duration, and estimated completion (useTransferDuration, getWithdrawalConfirmationDate). Without this field, those flows fall back to the standard challenge-period estimate.

This change sets fastWithdrawalTime to 86400000 (24 hours in ms) for HPP Mainnet and HPP Sepolia in packages/arb-token-bridge-ui/src/util/orbitChainsData.json, aligned with the public announcement.

Steps to test

1. Run the UI locally (e.g. from packages/arb-token-bridge-ui per repo README).
2. Select HPP Mainnet (or HPP Sepolia) as the child/source chain for a withdrawal toward Ethereum (or Sepolia).
3. Confirm the transfer panel / withdrawal flow shows a ~24 hour (or “1 day”) style confirmation estimate instead of the long default challenge period.
4. Optionally start a test withdrawal and confirm the estimated time remaining / completion logic uses the fast-withdrawal path (no need to wait for on-chain finality; UI copy and timers are enough to verify).

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[findmytrueself]

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