Bug Report

What did you do?

1. After expanding the tiflash, the tiflash node will automatically have a layer of label information: engine: "tiflash"
   2, When the pd is configured: replication. strictly-match-label: true
   3, This causes tiflash unable to start because replication. location-labels in the default pd config does not exist: engine layer configuration.

What did you expect to see?

1、tiflash start successfully
2、replication. location-labels can automatically recognize and add a new "engine" layer;

What did you see instead?

1、tiflash start failed；
2、replication. location-labels can not automatically recognize and keep old layer;

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

Release Version: v7.5.0
Edition: Community
Git Commit Hash: ef6ba85
Git Branch: heads/refs/tags/v7.5.0
UTC Build Time: 2023-11-16 10:31:04