Update Oracle connector deployment instructions for consistency

As part of the work to prepare the Debezium Oracle connector documentation for publication on the Customer Portal, update the deployment instructions to align with the way the information is presented for the other connectors.

In Q3 2020 the content of chapter 3.6 Deploying Debezium PostgreSQL connectors of the User Guide was updated based on observations recorded by Ramesh, as described in DBZ-2621. In 2021, similar corrections were applied to the documentation for the other connectors that are available downstream, with the eventual goal of creating a shared deployment module.

Because this work entails some complex restructuring and conditionalization, I'm separating it out from the other updates related to preparing the connector for Developer Preview/Technology Preview.