texlive: allow substitutes for texlive packages (#126458)

pkgs/tools/typesetting/tex/texlive/default.nix

@@ -131,6 +131,7 @@ let
 
     in if sha512 == "" then
       # hash stripped from pkgs.nix to save space -> fetch&unpack in a single step
+      # currently unused as we prefer to keep the sha512 hashes for reproducibility
       fetchurl {
         inherit urls;
         sha1 = if fixedHash == null then throw "TeX Live package ${tlName} is missing hash!"
@@ -144,8 +145,7 @@ let
         // passthru
 
     else runCommand "texlive-${tlName}"
-      ( { # lots of derivations, not meant to be cached
-          preferLocalBuild = true; allowSubstitutes = false;
+      ( {
           inherit passthru;
         } // lib.optionalAttrs (fixedHash != null) {
           outputHash = fixedHash;