fix(tf-checks): control terraform plan output based on show_plan flag

[sunnymor-cd]

📄 Terraform Plan Output Fix

📝 Description

Fixed Terraform plan output behavior to correctly respect enable_plan and show_plan inputs.
Plan output is now written to a file and displayed conditionally based on input flags.

🔧 Type of Change

• 🐛 Bug fix

🏷️ Workflow Category

• Terraform (tf-*)

✅ Checklist

• Code follows project style guidelines
• Self-review completed
• No new warnings introduced
• Changes tested locally and working as expected

🧪 Testing

• enable_plan=false → Plan step is skipped

• enable_plan=true + show_plan=true → Full plan output displayed

• enable_plan=true + show_plan=false → Only summary line displayed

• Tested without var_file input

[pendharevaibhav-cd]

LGTM!