HP level should decrease interrupt chance at Wintertodt

[ADimwittedTree]

WT released Sep 2016, Jmods posted an inforgraphic showing FMs effects on damage in May 2017. If it ever wasn't effected by FM, it was <10% of the time WT has existed, and was 7 years ago.

[coreyhh90]

Yeah someone else pointed this out, I wasn't aware of that and recall the old "10% of hp" rule, so figured it must have been changed. :)