fix: specify emcumbrance for acidchitin, plated leather, etc armor directly instead of using broken inheritance

[chaosvolt]

Checklist

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• I wrote the PR title in conventional commit format.
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Purpose of change

I was starting to work on something unrelated when I was reminded that #3861 is still a problem, screwing up acidchitin and plated leather items. Since I don't know how to fix it codewise I'm putting in a workaround.

Describe the solution

Converted the encumbrance definitions of acidchitin armor, plated leather armor, and fingerless glove variants to be explicitly set instead of relying on broken proportional and relative adjustments. Same thing I already had to do with superalloy armor. Even western boots and carbon fiber ballistic shields for that matter used it.

Describe alternatives you've considered

Tormenting Scarf into looking at the code to fix it.

Testing

1. Checked affected files for syntax and lint errors.
2. Checked the items they inherit from and did basic math to confirm the encumbrance values are what they're supposed to be.
3. Load-tested in compiled test build, confirmed acidchitin armor now actually has 15 encumbrance instead of 10.

Additional context

This has been broken for over a year aaaa