fix get_max_short and get_max_long

[wakamex]

fix a few problems with get_max_short:

• innacuracy previous noticed (fix market get_max_short #288)
• causing crash when running bots on goerlit testnet

[wakamex]

part of bug-squashing, we have a few other low hanging fruit to tackle first, but this will be a priority in a day or two

[dpaiton]

New Hyperdrive sol calculateMaxLong methodology here: delvtech/hyperdrive#302