only one pd instance have trace-region-flow config by query in v6.5.6

[River2000i]

Bug Report

What did you do?

1. use tiup deploy a v6.5.6 cluster

tiup playground v6.5.6 --db.port 4002 --db 1 --kv 1 --tiflash 0 --pd 3

2. check pd config

mysql> show config where name like "%pd-server.trace-region-flow%";
+------+----------------+-----------------------------+-------+
| Type | Instance       | Name                        | Value |
+------+----------------+-----------------------------+-------+
| pd   | 127.0.0.1:2382 | pd-server.trace-region-flow | true  |
+------+----------------+-----------------------------+-------+
1 row in set (0.01 sec)

mysql> select version();
+--------------------+
| version()          |
+--------------------+
| 5.7.25-TiDB-v6.5.6 |
+--------------------+
1 row in set (0.00 sec)

What did you expect to see?

seem the config is deprecated in
https://github.com/tikv/pd/blob/release-6.5/server/config/config.go#L1163-L1165

maybe can not get this config? only this pd instance print this log

and actually all pd instances have trace-region-flow config

What did you see instead?

What version of PD are you using (pd-server -V)?

Release Version: v6.5.6
Edition: Community
Git Commit Hash: 54bdbc3bfbc384229a59e47bdbdf19bc5969b468
Git Branch: heads/refs/tags/v6.5.6
UTC Build Time:  2023-11-28 05:25:32