Remove SHA-1 hash from BuildProducts

SHA-1 is deprecated and it will be expensive to compute with the
streaming NAR handler.

src/hydra-queue-runner/build-result.hh

@@ -11,7 +11,7 @@ struct BuildProduct
     nix::Path path, defaultPath;
     std::string type, subtype, name;
     bool isRegular = false;
-    nix::Hash sha1hash, sha256hash;
+    nix::Hash sha256hash;
     off_t fileSize = 0;
     BuildProduct() { }
 };