when change `tiflash` mounted disk in k8s, `tidb-dashboard` won't show new disk but old disk

[AkiraXie]

Bug Report

Please answer these questions before submitting your issue. Thanks!

What did you do?

1. tidb cluster in k8s
2. tiflash change mounted disk from /etc/hosts to /data0
3. disk capacity changed from 2.1tb to 3.6tb

What did you expect to see?

1. dashboard will show tiflash new disk info correctly

What did you see instead?

1. dashboard shows tiflash old disk info

What version of TiDB Dashboard are you using (./tidb-dashboard --version)?

[mornyx]

/assign