Use configured compression in hydra-compress-logs service

nixos-modules/hydra.nix

@@ -459,10 +459,12 @@ in
     # logs automatically after a step finishes, but this doesn't work
     # if the queue runner is stopped prematurely.
     systemd.services.hydra-compress-logs =
-      { path = [ pkgs.bzip2 ];
+      { path = [ pkgs.bzip2 pkgs.zstd ];
         script =
           ''
-            find ${baseDir}/build-logs -type f -name "*.drv" -mtime +3 -size +0c | xargs -r bzip2 -v -f
+            set -eou pipefail
+            compression=$(sed -nr 's/compress_build_logs_compression = ()/\1/p' ${baseDir}/hydra.conf)
+            find ${baseDir}/build-logs -type f -name "*.drv" -mtime +3 -size +0c | xargs -r $compression -v -f
           '';
         startAt = "Sun 01:45";
       };