Confusing error message when not passing certificate paths correctly with HTTPS PD URI

[liuzix]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do? If possible, provide a recipe for reproducing the error.
   /cdc cli changefeed create --pd=https://db-pd:2379 --sink-uri="mysql://root:*****@*****:4000/"

2. What did you expect to see?

• CDC reporting that certificates are expected

3. What did you see instead?

• PD endpoint scheme should be http

4. Versions of the cluster

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

     v4.0.11
     

   • TiCDC version (execute cdc version):

     v4.0.11
     

[Rustin170506]

I am working on this.

[Rustin170506]

/assign