fix(strength): Remove threat reduction, increase crit chance

Tweaks the STR attribute's algorithmic effects. (1) Task "redness" no longer declines faster with high STR. (2) The 3% chance of a critical hit is multiplied by a percentage factor equal to STR. (3) The value of STR in dealing damage to bosses is increased by 25% (.5% instead of .4%).

Fixes [HabitRPG issue 2464](https://github.com/HabitRPG/habitrpg/issues/2464).