You could call it Standards, although several of the things you list would be part of the
TDD (Technical Design Document). Backup plan would usually be part of the TDD. The test
plan is a separate document.

Yeah most of it is covered by TDD (or we call ours the TDO, but it's the same thing).
Our Technical Design Overview document starts with:
Purpose
Give a high level overview of all technologies required to make the game according to the game design. This document will list all systems, tools, 3rd party technologies, and pipelines. This document will also provide a brief description of the engine and architecture, identify whether technologies used are new or existing, present the technology schedule and the engineering staff plans. The TDO will also point out risks of various areas of technology and possible mitigations for those risks including dependencies.
...and covers most of your bullet points.

In general, we call these kinds of procedure documents "bibles" -- e.g. the art bible, the coding bible.