Ignore tables without a valid pgschema_name value

[vaibhav-yb]

If a user creates a table old_table with an older version of YugabyteDB, let's say 2.11 and upgrades to a version with the CDCSDK changes, then the old_table would not have the metadata in its TableInfo which has the pgschema_name value. This in turn causes a regression in Debezium connector since it utilizes the schema name to parse the name of the tables, so after upgrade, while filtering the tables, if pgschema_name value is not found in any of the tables, the Debezium connector for YugabyteDB throws a NullPointerException.

This PR addresses the issue and adds the logic to ignore the tables which do not have a pgschema_name value, consequently meaning that the connector is ignoring the tables created using the older versions of YugabyteDB.

Steps to test:

1. Create a table old_table with YugabyteDB version 2.11 on platform
2. Upgrade to 2.13.2 and create another table new_table
3. Create a stream ID and start streaming for new_table
4. Insert a few rows
5. Update a few rows
6. Delete the rows
7. Restart the connector and repeat steps 4-6

[suranjan]

Please take care of the comment.