feat(balance): rebalances for military helipad

[chaosvolt]

Purpose of change

And this continues the work on overhauling military locations, now touching helipads.

Describe the solution

1. As with military bases, hardened the main building to have tougher glass and brick exterior walls, along with locked metal doors.
2. Repositioned the two sealed-off rooms a bit and replaced the sealed shutter doors with regular locked metal doors.
3. Replaced the multiple tiny chances of spawning heli wrecks and a tiny chance of a proper copter with a single higher chance to spawn two military helicopters, placed to ensure they more reliably have room to spawn.
4. Moved the fuel pumps in a bit to give more space to the helis.
5. Reworked the loot of the locked rooms a bit to have a wider variety of potential results, including decent odds of spawning standard ballistic armor instead of stored guns, and weighting the other storage room more towards specificially mil-spec vehicle parts.
6. Replaced guardrails at the entrance to chain gates, added some in the back to allow the potential to load and unload supplies there
7. Reworked the vehicle weights of mil_helicopters to be 50/50 between intact helis and wrecked ones instead of only medevac ones being 50/50 and the rest almost never spawning intact.
8. Swapped out the janky zombie soldier spawns with proper place_monster usage, and spawn them indoors so they won't infight with the turrets. In return...
9. The outside area where the helis spawn, predictably, may have a lil robot as a treat.
10. Fixed that one standing tank spawning with a roof over it due to having floor underneath.
11. Removed an unused spawn in the helipad location.
12. Deleted the full overrides contained in No Hope because again always such a mess augh.

Describe alternatives you've considered

I wanted to adjust the locked-up rooms such that they could have a computer console placed near them to open shutter doors instead of using basic pickable doors, but problem I ran into there was can't ensure a spot for the console that won't catch any of the nearby garage doors in its effect radius.

Testing

1. Checked affected files for syntax and lint errors.
2. Load-tested in compiled test build and spawned in to ensure the location looked decent.

Screenshots, Before:

Screenshots, After:

Additional context

Side note: in terms of where [ 0, 0 ] is on the vehicle relative to other vehicles in the same vehiclegroups, APCs and apache copters in particular have some noticeably fucking cursed center placement. I spotted the former while briefly considering having this location also spawn a military vehicle, finding that the APC would spawn off-center and dangerously close to the garage door when other vehicles were aligned just fine, before deciding it was better to save that empty space for monster spawns.

For the latter, it's still prone to making apaches spawn with their nose embedded in the fence, when other helis spawn in a more reasonable spawn.

Checklist

[Admiral-Daala1541]

Silly question, are you gonna touch the zed spawns here.

Because I hate burners with a passion for being gas zeds with RNG as to whether or not they burn down the whole zone.

[chaosvolt]

I haven't currently touched the monstergroups in question, but I do think it'd be nice to follow up on this by tweaking how the flamer death function works. Ideally I'd like it to be able to either track the damagetype of the killing blow or else whether the monster had the onfire status when it was killed, and if so only trigger the death explosion if hit by heat-type weapons (with maybe a much smaller chance if killed by electric or ballistic damage).

If tracking the status of a now-dead monster during its death function is impossible, it might be better to instead convert it to some sort of monster flag behavior that's checked for when the monster takes damage, with it having a chance of exploding when shot by certain damagetypes.