texlivePackages.*: set `meta.{platforms,hydraPlatforms}`

pkgs/tools/typesetting/tex/texlive/build-texlive-package.nix

···
     '';
     # discourage nix-env from matching this package
     priority = 10;
+    platforms = lib.platforms.all;
+    # These create a large number of jobs, which puts load on Hydra
+    # without any appreciable benefit (as the combined packages already
+    # cause them all to be built and cached anyway).
+    hydraPlatforms = [ ];
   } // lib.optionalAttrs (args ? shortdesc) {
     description = args.shortdesc;
   };