Double iteration in searching exit pools

[KaiserKarel]

Nit:

quasar/smart-contracts/contracts/lp-strategy/src/icq.rs

Line 108 in cc7d85a

let base = exit_pool

iterates twice, which isn't necessary at all. We can fold with a (bool, bool) accumulator or write our own extension trait if itertools doesn't provide anything so we can short circuit.