Remove deprecated security-considerations workflow files

[wz-gsa]

We detected deprecated security-considerations automation files in this repository.

Detected

• .github/workflows/security-considerations.yml

Why this matters

This cleanup reduces supply-chain and maintenance risk.

Plan

• Remove the deprecated files
• Open a PR for peer review
• Merge after approval

Policy checks

• Date (ET): 2026-03-05

Tracking

• Inventory run id: bd274315-e7c3-4a53-b395-df593398d73d
• Epic: cloud-gov/private#2851

If you believe these files are still required for this repo, comment with context before merge.