Lock all Tree mutations behind infusions

[TDHooligan]

It wasn't rolled back, the PR that added the infusions just lowered their random chance to the default of 8%: https://github.com/goonstation/goonstation/pull/11229

the complaint could still have some weight - with 5 mutations (excluding the money tree), the HYPNewMutation check (called by planting a seed, possibly elsewhere) actually checks the odds of each mutation @ 8%, rather than an 8% chance to get one of them. it makes it a 34% chance whenever a seed is planted to mutate, which might be a bit high.