feat(balance): dial back nerf to skill impact on butchery a bit

[chaosvolt]

Purpose of change

So, a lot of feedback has come in suggesting that #3719 undervalued the impact of skills on butchery and dissection yields. A lot of this is ultimately because dissection isn't as granular as it could probably afford to be, so going so far as to break up, for example, the electronics skill being divided by 4 means it takes several levels for it to kick in and actually bump up your success result by any amount at all.

Describe the solution

1. In activity_handlers.cpp, changed activity_handlers::butcher_finish so that the baseline definition of skill_level is back to using survival skill directly instead of cutting it in half (so result is a clean 0-10 instead of randomized 0-7).
2. Furthermore, made both skills being checked for when dissecting grant 1 every 2 points instead of devaluing electronics so heavily, and made it so the impact of tool quality is increased by 1.25x.

Success rates with the following tool qualities:

Fine Cutting	0/0 skills	3/3 skills	5/5 skills	10/10 skills
1	10%	20% -> 30%	40% -> 50%	80% -> 100%
2	20%	30% -> 40%	50% -> 60%	90% -> 100%
3	30%	40% -> 50%	60% -> 70%	100%
5	50%	60% -> 70%	80% -> 90%	100%

Fine cutting level 4 not implemented in vanilla, so omitted. Tested with average dexterity to avoid the weird RNG impact it adds. Goal here was setting it so you get reliably high success rate with a scalpel when both your skills hit level 5, while having the surgical CBM lets you reach perfection with only 3 in both skills.

Describe alternatives you've considered

Making the roll more granular would be nice but that'd require all of the processing involving roll_butchery and the functions that use them to deal in float instead of int.

Testing

1. Compiled and load-tested.
2. Tested dissecting a bunch of stuff in debug mode to get the above table.
3. Checked affected file for astyle.

Additional context

Checklist