fix: mre actually gives 1 pur tablet this time

[chaosvolt]

Purpose of change

So I could've sworn I nerfed MREs to not yield half a dozen purification tablets due to how much more effective they are. Turns out, in #3297 I edited the mre_accessory uncraft...which was long ago obsoleted, MREs actually produce their accessories via the mre_accessory_list CRAFTING REQUIREMENT instead. Auuuugh.

Describe the solution

Toned down number of tablets given by mre_accessory_list from 6 to 1, like I tried and failed to do already, derp. It still goes from "meant to make 1.5 liters of water" to 2 liters worth, 6 liters from a single MRE meanwhile is not intended yield. :3

Describe alternatives you've considered

screm

Testing

1. Checked affected file for syntax and lint errors.
2. Ported JSON change to playthrough build, confirmed taking apart an MRE ACTUALLY only yields a single tablet now.

Additional context

A single tablet cleans 2 liters of water instead of 250 ml, as of this PR: #2832

Checklist

[Firestorm01X2]

Ready