[watsonx-orchestrate] Add support for the region `br-sao`

[imprateeksh]

Description

• It seems the region br-sao is now part of the region dropdown but is not supported via code.
• This region must be integrated in the code with proper test coverage to guarantee support.
• The test regions should also be updated.

Current code:

Cloud console:

Other places where this change should be done -
*
*

[Aditya-ranjan-16]

Changes added in PR : #170

Closing the issue