sharding: Move chown/chmod into where the files are written.

scripts/lib/sharding.py

@@ -1,8 +1,10 @@
 #!/usr/bin/env python3
 import argparse
 import filecmp
+import grp
 import json
 import os
+import pwd
 import subprocess
 import sys
 
@@ -77,6 +79,14 @@ def write_updated_configs() -> None:
         data = {"shard_map": shard_map, "shard_regexes": shard_regexes}
         sharding_json_f.write(json.dumps(data) + "\n")
 
+        for fh in (nginx_sharding_conf_f, sharding_json_f):
+            os.fchown(
+                fh.fileno(),
+                pwd.getpwnam("zulip").pw_uid,
+                grp.getgrnam("zulip").gr_gid,
+            )
+            os.fchmod(fh.fileno(), 0o644)
+
 
 parser = argparse.ArgumentParser(
     description="Adjust Tornado sharding configuration",