BUG: Move copilot-setup-steps.yml to correct directory

As per documentation in:
https://docs.github.com/en/enterprise-cloud@latest/copilot/how-tos/use-copilot-agents/coding-agent/customize-the-agent-environment#preinstalling-tools-or-dependencies-in-copilots-environment

Follow-up to PR: #5632

Author: dzenanz