refactor(overlays): consolidate test patches

overlays/patches/default.nix

@@ -6,10 +6,9 @@ _final: prev:
 
   pythonPackagesExtensions = prev.pythonPackagesExtensions ++ [
     (_pythonFinal: pythonPrev: {
-      backrefs = import ./backrefs { inherit (pythonPrev) backrefs; };
       pytest-xdist = import ./pytest-xdist { inherit (pythonPrev) pytest-xdist; };
+      scipy = import ./scipy { inherit (pythonPrev) scipy; };
       sentry-sdk = import ./sentry-sdk { inherit (pythonPrev) sentry-sdk; };
-      torchcodec = import ./torchcodec { inherit (pythonPrev) torchcodec; };
     })
   ];
 }