docs: fix reference to nonexistent support_ticket_agent example

[jaathavan18]

Summary

• Replaces hardcoded support_ticket_agent with generic your_agent_name in ENVIRONMENT_SETUP.md PowerShell example
• The exports/ directory is gitignored so the referenced agent doesn't exist on fresh clones
• Now matches the Linux/macOS example directly above it

Closes #3155

Test plan

• Verify the PowerShell example is consistent with the Linux example above it