Flat fees for IBC transactions

[mturkia]

Background

IBC relayers are paying the gas price of the destination chain, and with the volume of Osmosis, relayer can perform thousands of transactions per day. The introduction of minimum gas fees that many validators have done to fight 0fee spam transactions, relayers face problem of choosing gas fees that will get included into block fast but does not end up costing too much. And this is very hard when validators have min gas prices varying a lot.

Suggested Design

I suggest that we set a flat for IBC transactions, similar to what is done with arbitrage fees. This IBC fee can be set to 0 or small fee that still guarantees that IBC transactions are included into block rapidly. This would take the balancing/guessing game out of setting the relayer fees.

Acceptance Criteria

• [ ] IBC transactions are accepted with flat fee