[DATA] Remove `srd-2014` `Mithral Armor (Hide)` and `Adamantine Armor (Hide)`

[calumbell]

Bug description

Hide Armor variations of Mithral and Adamantine Armor are included in the srd-2014 V2 data. These variations are specifically disalowed in the source material and should be deleted.

Steps to Reproduce

1. Visit the top-level magic items page on the Beta Open5e website
2. Filter the magic items using the query text "(hide)" to capture Mithral Armor (Hide) and Adamantine Armor (Hide). Note that they exist.
3. Consult the SRD 5.1 source data regarding "Adamantine Armor" (pp. 207) and "Mithral Armor" (pp. 231). Both explicitly exclude Hide Armor variants.