update default driver for oracle, postgresql

update default driver for oracle, postgresql

The default DBAPI driver for the Oracle Database dialect has been changed
to ``oracledb`` instead of ``cx_oracle``. The ``cx_oracle`` driver remains
fully supported and can be explicitly specified in the connection URL
using ``oracle+cx_oracle://``.

The default DBAPI driver for the PostgreSQL dialect has been changed to
``psycopg`` (psycopg version 3) instead of ``psycopg2``. The ``psycopg2``
driver remains fully supported and can be explicitly specified in the
connection URL using ``postgresql+psycopg2://``.

Fixes: #13010
Change-Id: Ie75810f4c3af609d20da63289d2662dfa2385ca2