[DTOSS-12318] - chore(iac): remove unused variables from dev environment

[josielsouzanordcloud]

Description

This PR removes two unused variables from the dev environment's variables.tfvars file. The variables vnet_address_space and enable_gateway_test_vm are no longer required for the current configuration, thus they have been deleted to clean up unnecessary settings.

Type of change

• Bug fix
• New feature
• Breaking change
• Infrastructure change
• Pipeline / CI
• Documentation update
• Refactor

Jira link

DTOSS-12318

Review notes

• Removed vnet_address_space from infrastructure/environments/dev/variables.tfvars.
• Removed enable_gateway_test_vm from infrastructure/environments/dev/variables.tfvars.

Breaking changes

None

Impact

• No impact on deployment or services.
• No change to security configuration.
• No cost implication.

Review checklist

• No hardcoded secrets, credentials, or tokens
• PR title follows correct format (with ticket prefix if ticket provided, without if not)
• terraform plan reviewed — no unintended resource destruction
• Mandatory tags on all new resources
• Resource locks on critical resources
• Variable changes propagated to all environment .tfvars files
• State file impact assessed