fix: handle the situation that opensearch_failover does not exist

[gatici]

Description of issue or feature:

This PR fixes Terraform evaluation errors in the large deployment configuration when the failover orchestrator is optional.

When failover is not provided, Terraform was attempting to dereference var.failover.model_uuid and access outputs from modules created with for_each, causing failures during terraform module validation.

Solution

• Guarded access to var.failover.model_uuid in locals 1
• Fixed output handling by using try(..., null) to avoid failures when failover is not deployed 2 3

How was this change tested?

• Manually
• Unit tests
• Integration tests

Checklist

• I have added or updated any relevant documentation.
• I have cleaned any remaining cloud resources from my accounts.

[akram09]

Thanks @gatici

[akram09]

Small comment.
I was thinking that we should fix the terraform provider version so that it don't take other versions and make the pipeline fails again

[Mehdi-Bendriss]

Thanks Gulsum! just a minor comment on the TF version