feat(balance): sanity-check spawns in drug deal map extra

[chaosvolt]

Checklist

Required

• I wrote the PR title in conventional commit format.
• I ran the code formatter.
• I linked any relevant issues using github keyword syntax so it can be closed automatically.
• I have committed my changes to new branch that isn't main so it won't cause conflict when updating main branch later.

Optional

Purpose of change

Another lil entry in my todo list, we've received multiple complaints about drug dealer map extras being a cornucopia of basically-free guns due to how many bodies spawn there.

Describe the solution

1. Condensed the weapon and gunmod spawns in drugdealer into a single distribution. Instead of rolling for a melee weapon, a gun, AND a gunmod it picks one of each with about 50% odds of it being a gun. Effectively reduces the chance of getting a gun from 50% per corpse (reminder, each map extra will have up to a dozen corpses) to 25%. Additionally, per feedback rifles have been removed from the selection in favor of more SMGs
2. Additionally condensed the snacks, booze, and soft drugs into a single distribution so that the separate rolls for harder stuff with stand out more and not be mixed with a bunch of milder stuff.
3. Lastly, increased the relative chance of a dead gang member and/or cop spawning as a zombie instead of an intact corpse, from a mere 10% chance to a 25% chance.

Describe alternatives you've considered

Screaming.

Testing

1. Checked affected file for syntax and lint errors.
2. Load-tested in compiled test build.
3. Did an itemgroup test before and after. Before, the itemgroup test went on and on (due to feat: raise amount of itemgroup tests from 100 -> 1000 #5033 I warned @Lamandus this would be a consequence) while the result afterward looked more reasonable.

This should give you a vague idea of the difference, once I got to 6 entire pages of screenshots for the itemgroup results for the before test I kinda just gave up because as you can see I barely like a third of the way through it:

Additional context

[RoyalFox2140]

I think it's ok where it is but if people really want rare weapons it will appease some people. Few of the actual firearms spawned at drug deals are useful beyond earlygame or as a panic weapon so it was primarily a way of improving commonality of handguns and smg's + alleviating earlygame problems of finding firearms from the other PR's that slashed rates dramatically.

[Firestorm01X2]

Looks like it is ready.

[Firestorm01X2]

Ready