chore: Filter out "empty" liquidity sources

[MartinquaXD]

Background

Some solvers report Ignoring ill-defined AMM "3": Attempt to create an AMM with non-positive token balance. indicating that we are sending "empty" AMMs.

There are definitely some constant product AMMs that have either 0 or very little liquidity. It probably makes sense to filter out any pool that has < X$ worth of tokens in them.

Examples:

• https://etherscan.io/address/0x4db44282701e28e0c2ac76188b8489298aabbc04
• https://etherscan.io/address/0xe2deb0d3578f99fb1eeaaf4c5f25a441bfd75d9f
• https://etherscan.io/address/0xa65ab9b0d2f070eb9c68615b723d9ed95b36ba22

instance.json

Acceptance criteria

If an AMM does not actually have any liquidity we should not send it to the solver. Additionally we should not attempt to fetch its state again on the next block if it's empty.

[blackbera]

I will take a shot at this if the last PR wont be merged! @fleupold @MartinquaXD