ci: reduce number of unnecessary jobs

[edersonbrilhante]

Description

• Separate MiniStack smoke tests from the Terraform lifecycle workflow.
• Keep Terraform lifecycle jobs focused on Terraform/OpenTofu changes.
• Add a dedicated smoke-test workflow for Lambda and MiniStack lifecycle validation.
• Update the MiniStack service image to 1.5.13 with its pinned SHA256 digest.
• Configure Dependabot to monitor the workflow directory for MiniStack image updates.

Test Plan

• GitHub Actions will validate the updated workflow configuration.
• The smoke-test workflow builds the webhook and control-plane Lambda distributions.
• The smoke-test workflow runs the webhook and pool lifecycle tests against MiniStack.
• Terraform lifecycle validation remains covered by the existing workflow.

Related Issues

Not applicable.

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

• .github/workflows/ministack.yml