[DTOSS-11566] - feat: Enable postgres high availability

[josielsouzanordcloud]

Description

Updates the PostgreSQL Flexible Server Terraform module to support high availability configuration. This change adds a new variable postgres_enable_high_availability that allows consumers of the module to enable zone-redundant high availability for their PostgreSQL deployments.

Changes made:

• Added postgres_enable_high_availability variable to the module
  • Type: bool
  • Nullable: false
  • Default: false
  • Enables zone-redundant high availability when set to true

This is a module template change that enables high availability support across all PostgreSQL Flexible Server deployments that use this module.

Context

High availability is a critical requirement for production database workloads. This module enhancement enables teams to easily configure zone-redundant PostgreSQL deployments, providing:

• Automatic failover: Synchronous replication to standby server in different availability zone
• Business continuity: Protection against zone-level failures
• Data protection: Zero data loss during failover events
• Production readiness: Meets enterprise SLA requirements

By making this a configurable module parameter with a safe default (false), teams can:

• Opt-in to high availability for production environments
• Keep costs lower for non-production environments (dev, review and preprod)
• Maintain consistent infrastructure-as-code patterns across environments

Type of changes

• Refactoring (non-breaking change)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would change existing functionality)
• Bug fix (non-breaking change which fixes an issue)

Checklist

• I am familiar with the contributing guidelines
• I have followed the code style of the project
• I have added tests to cover my changes
• I have updated the documentation accordingly
• This PR is a result of pair or mob programming

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Sensitive Information Declaration

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• I confirm that neither PII/PID nor sensitive data are included in this PR and the codebase changes.

[saliceti]

Can you please update the terraform doc?

[mrlockstar]

LGTM