op mode: T6348: SNAT op-mode fails with flowtable offload entries

(cherry picked from commit 1cba74f)

src/op_mode/nat.py

@@ -263,7 +263,7 @@ def _get_formatted_translation(dict_data, nat_direction, family, verbose):
                     proto = meta['layer4']['protoname']
             if direction == 'independent':
                 conn_id = meta['id']
-                timeout = meta['timeout']
+                timeout = meta.get('timeout', 'n/a')
                 orig_src = f'{orig_src}:{orig_sport}' if orig_sport else orig_src
                 orig_dst = f'{orig_dst}:{orig_dport}' if orig_dport else orig_dst
                 reply_src = f'{reply_src}:{reply_sport}' if reply_sport else reply_src