Secondary debt dust balances are not truncated
Dust balances in primary debt are truncated toward zero. However, this truncation was not performed against secondary debts.\\n```\\nFile: VaultAccount.sol\\n    function updateAccountDebt(\\n..SNIP..\\n        // Truncate dust balances towards zero\\n        if (0 < vaultState.totalDebtUnderlying && vaultState.totalDebtUnderlying < 10) vaultState.totalDebtUnderlying = 0;\\n..SNIP..\\n    }\\n```\\n\\n`vaultState.totalDebtUnderlying` is primarily used to track the total debt of primary currency. Within the `updateAccountDebt` function, any dust balance in the `vaultState.totalDebtUnderlying` is truncated towards zero at the end of the function as shown above.\\n```\\nFile: VaultSecondaryBorrow.sol\\n    function _updateTotalSecondaryDebt(\\n        VaultConfig memory vaultConfig,\\n        address account,\\n        uint16 currencyId,\\n        uint256 maturity,\\n        int256 netUnderlyingDebt,\\n        PrimeRate memory pr\\n    ) private {\\n        VaultStateStorage storage balance = LibStorage.getVaultSecondaryBorrow()\\n            [vaultConfig.vault][maturity][currencyId];\\n        int256 totalDebtUnderlying = VaultStateLib.readDebtStorageToUnderlying(pr, maturity, balance.totalDebt);\\n        \\n        // Set the new debt underlying to storage\\n        totalDebtUnderlying = totalDebtUnderlying.add(netUnderlyingDebt);\\n        VaultStateLib.setTotalDebtStorage(\\n            balance, pr, vaultConfig, currencyId, maturity, totalDebtUnderlying, false // not settled\\n        );\\n```\\n\\nHowever, this approach was not consistently applied when handling dust balance in secondary debt within the `_updateTotalSecondaryDebt` function. Within the `_updateTotalSecondaryDebt` function, the dust balance in secondary debts is not truncated.
Consider truncating dust balance in secondary debt within the `_updateTotalSecondaryDebt` function similar to what has been done for primary debt.
The inconsistency in handling dust balances in primary and secondary debt could potentially lead to discrepancies in debt accounting within the protocol, accumulation of dust, and result in unforeseen consequences.
```\\nFile: VaultAccount.sol\\n    function updateAccountDebt(\\n..SNIP..\\n        // Truncate dust balances towards zero\\n        if (0 < vaultState.totalDebtUnderlying && vaultState.totalDebtUnderlying < 10) vaultState.totalDebtUnderlying = 0;\\n..SNIP..\\n    }\\n```\\n