fix(variable): Fix for ternary type mismatch and validation

[r351574nc3]

what

• Fix for

  
  │ Error: Inconsistent conditional result types
  │
  │   on .terraform/modules/ec2_client_vpn/main.tf line 9, in locals:
  │    9:   saml_provider_arn          = local.federated_enabled ? try(aws_iam_saml_provider.default.*.arn, var.saml_provider_arn) : ""
  │     ├────────────────
  │     │ aws_iam_saml_provider.default is empty tuple
  │     │ local.federated_enabled is false
  │     │ var.saml_provider_arn is null
  │

│ The true and false result expressions must have consistent types. The given expressions are tuple and string, respectively.

## why
* Error prevents deploying in infrastructure repository

## references
* N/A