Reduce Harvester's no-xenorain-death explosive damage requirement to >121 for lv1 rifle alt

[WhenTanksFly]

From https://steamcommunity.com/app/563560/discussions/2/3361397532251132492/:

damage type with which harvester died must be an explosion damage amount must be over 135 damage amount must be at least 2 times higher than harvester's health before the damage was dealt

So the Grenade Launcher can block the on-death xenomite release when used by any marine, but Assault Rifle's underbarrel grenade of 128 base damage necessarily requires an explosive bonus, which feels unfair. If we wanna follow the theme of a big singular boom preventing Harvester's final gift, nerf the minimal required damage to anywhere from 121 (blocking off non-direct Jaeger GL hit) to 128. Surely nobody would mind a basic rifle buff.