fix: correct region list

[imprateeksh]

Description

This PR removes the ca-tor region from the list of regions.
Reason :

• In the current variations, the list of regions provided is - [us-south , eu-de, eu-gb, au-syd, jp-tok, ca-tor]
• But there are some regions which are not supported by some of the services -
  ca-tor, and us-east are not supported for watsonx Assistant and watson Discovery
• Another restriction is with watsonx-data that the plan region combination requires no KMS for ca-tor and au-syd region but that will be handled by the code.

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[terraform-ibm-modules-ops]

🎉 This PR is included in version 5.0.3 🎉

The release is available on:

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• v5.0.3

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