Make item_armor25 spawn 25 armor instead of mega armor.

There are quite a few maps that are total garbage to play in duel or with low player count, because they have two mega armors almost in the same place.

When editing kaznexdm1 in Radiant, I noticed that it did not actually contain mega armors, but "item_armor25" instead. When checking the code I confirmed that for whatever reason, Xonotic spawns mega armors from 25 armor entries.

In the same code "item_armor_large" was also set to mega armor. This sounds to me a bit like it should be 50 armor instead, but unlike "item_armor25" I'm not really sure what "large" is referring to.

I suspect that this problem is not limited to this map, but that it breaks many other maps the same way and turns them into unplayable cringe crap.

I see absolutely no reason why 25 armor should spawn mega armor.