Postgres-cdc: self-signed cert cannot pass the SSL/TLS validation

[StrikeW]

Describe the bug

See the log

Error message/log

Executor error: Connector error: Postgres error: error performing TLS handshake: error:0A000086:SSL routines:tls_post_process_server_certificate:certificate verify failed:ssl/statem/statem_clnt.c:1889:: unable to get local issuer certificate: error:0A000086:SSL routines:tls_post_process_server_certificate:certificate verify failed:ssl/statem/statem_clnt.c:1889:;

To Reproduce

No response

Expected behavior

For require or prefer ssl.mode, we can skip the verification for self-signed cert.

How did you deploy RisingWave?

No response

The version of RisingWave

No response

Additional context

#15690

[hzxa21]

#16319 adopts this approach: "For require or prefer ssl.mode, we can skip the verification for self-signed cert."

[StrikeW]

#16319 adopts this approach: "For require or prefer ssl.mode, we can skip the verification for self-signed cert."

nit: For require or prefer ssl.mode, we don't verify the peer certificate.