refactor(nix-compat/derivation): use ATerm for output_paths test r/6833

Due to the lack of a ATerm parser, we were previously loading the JSON
fixtures to construct our Derivation structs to run the output path
calculations with.

However, as we now have a ATerm parser, we can load the ATerm
representation directly.
This also means we can test the output path calculation for non-UTF8
Derivations.

Change-Id: I0e53f41a23566b5ad5f0fed12724e02a10b02707
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9731
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Reviewed-by: Connor Brewster <cbrewster@hey.com>

0 files changed, 0 insertions, 0 deletions