Failed to create changefeed after scale-in pd

[wk989898]

What did you do?

As depicted in pingcap/tiflow#12004. Create a issue for the convenience of cherry-pick.

What did you expect to see?

No response

What did you see instead?

N/A

Versions of the cluster

Upstream TiDB cluster version (execute SELECT tidb_version(); in a MySQL client):

(paste TiDB cluster version here)

Upstream TiKV version (execute tikv-server --version):

(paste TiKV version here)

TiCDC version (execute cdc version):

(paste TiCDC version here)