Investigate solver settings to make setting candidate asset capacity to zero viable

Sadly setting candidate asset capacity to zero results in commodity prices of zero, which is not good. We should investigate whether there's any HiGHS setting we can change to fix this. The full list is here: https://ergo-code.github.io/HiGHS/dev/options/definitions/

I had a quick look and tried toggling the `presolve` option, but that didn't help matters.