RENAME TABLE will fail if the source database name is not specified in a cross-database rename operation

[lidezhu]

What did you do?

This issue mirrors the one reported in #2189. The fix in #2218 only addresses scenarios where the source database name is explicitly provided. If it is not specified, the rename table operation still fails.

What did you expect to see?

No response

What did you see instead?

None

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)