user export: Ignore realm icon and logo.

These are not considered to be "personal"
info, even if you upload them, so we
don't export them.

Generally the only folks who upload
these are admins, who can easily get
them in other ways. In fact, anybody
can get these via the app.

zerver/lib/export.py

@@ -1398,6 +1398,8 @@ def export_uploads_and_avatars(
             output_dir=emoji_output_dir,
             realm_emojis=realm_emojis,
         )
+
+        if user is None:
             export_realm_icons(
                 realm,
                 local_dir=os.path.join(settings.LOCAL_UPLOADS_DIR),
@@ -1451,6 +1453,7 @@ def export_uploads_and_avatars(
             valid_hashes=emoji_paths,
         )
 
+        if user is None:
             export_files_from_s3(
                 realm,
                 handle_system_bots=handle_system_bots,