[EASY] Change slippage wrapper for consistency with old slippage query

[fhenneke]

This PR makes the slippage query wrapper consistent with the old slippage query.

• The blockchain parameter is set to ethereum. With this change, solver rewards does not have to add an additional parameter right now when querying slippage.
• The return type is changed to floating point numbers. This removes the need to have an additional conversion from within solver rewards.

This wrapper will be removed once we have to time to adapt the solver rewards script to the format of the new slippage query (or we remove that query and use a local database).

[harisang]

@fhenneke I don't see any change related to this

The return type is changed to floating point numbers. This removes the need to have an additional conversion from within solver rewards.

[harisang]

Probably forgot to include the edit on the slippage query

[fhenneke]

Probably forgot to include the edit on the slippage query

True. I pushed that fix as well now.

[harisang]

Approving but i guess this fix should be either on the 4070065 query side or in the payouts script itself

[fhenneke]

I think the slippage query itself should use integers.

At some point we need to change the solver rewards script to handle those values correctly. Until then, this wrapper provides compatibility with the current version of solver rewards.