fix(tf-checks): skip azure/login when AZURE_CREDENTIALS is not set

[anmolnagpal]

Why\nTerraform module repos that don't pass provider inherit the azurerm default and currently fail early at azure/login@v2 when AZURE_CREDENTIALS is not configured.\n\n## What\n- Add a credentials guard to both Azure login steps in .github/workflows/tf-checks.yml:\n - inputs.provider == 'azurerm' && secrets.AZURE_CREDENTIALS != ''\n\n## Impact\n- Prevents false CI failures in non-Azure module repos using this reusable workflow\n- Keeps Azure auth enabled when credentials are actually provided\n

[anmolnagpal]

Why

Terraform module repos that don't pass provider inherit the azurerm default and can fail early at azure/login@v2 when AZURE_CREDENTIALS is not configured.

What

• Add a credentials guard to both Azure login steps in .github/workflows/tf-checks.yml:
• inputs.provider == 'azurerm' && secrets.AZURE_CREDENTIALS != ''

Impact

• Prevents false CI failures in non-Azure module repos using this reusable workflow.
• Keeps Azure auth enabled when credentials are actually provided.