Properly return cost from `is_precompile` at `frontier_precompiles` implementation

https://github.com/humanode-network/humanode/pull/848#pullrequestreview-1808984230

- https://github.com/polkadot-evm/frontier/pull/1058
- https://github.com/polkadot-evm/frontier/pull/1039