Revisit gas fees in scripts

[zajck]

During the upgrade on polygon mainnet, the script was failing with "transaction underpriced" error. It worked only after getFees was changed to return gasPrice instead of EIP-1559 compliant maxPriorityFeePerGas and maxFeePerGas.
This resulted in much more expensive tx fees overall.

The problem was not present on any other networks where we upgraded or deployed v2.3.0 version.

Investigate how to properly handle fees on all networks.