Using ML metadata postgres SSL connection options don't work for `sslMode=require`

[dhirajsb]

Checked with both 1.14.0 and 1.15.0.dev20230814 versions of mlmd Docker images.

Trying to use Postgres SSL configuration options with sslMode=require causes the following error:

WARNING: Logging before InitGoogleLogging() is written to STDERR
I1122 01:34:29.953503     1 postgresql_metadata_source.cc:208] Connecting to database. 
E1122 01:34:29.953600     1 postgresql_metadata_source.cc:211] PostgreSQL error: sslmode value "require" invalid when SSL support is not compiled in
F1122 01:34:29.953652     1 metadata_store_server_main.cc:555] Check failed: absl::OkStatus() == status (OK vs. INTERNAL: PostgreSQL metadata source error: connection pointer is NULL
) MetadataStore cannot be created with the given connection config.
*** Check failure stack trace: ***

Searching the error on the web suggests that the libpq library included in mlmd Docker image was not compiled with --with-openssl configure option.

Is this an issue in the image, or are we missing some other option when using the Docker image?

[rareddy]

@XinranTang can help us with correcting the build? thank you.