Remove non-functional OAuth remote servers from registry

Removed 20 OAuth remote servers that are not working based on testing results. These servers had various issues including redirect URL restrictions, missing OAuth discovery endpoints, DCR failures, or have been shut down.

Remote servers removed:
- atlassian-remote: Redirect URL not allowed
- box-remote: No DCR for box
- canva: Redirect URL not allowed
- cloudinary-analysis: Pending OAuth discovery fix
- cloudinary-asset-management: Pending OAuth discovery fix
- cloudinary-environment-config: Pending OAuth discovery fix
- cloudinary-mediaflows: Pending OAuth discovery fix
- cloudinary-structured-metadata: Pending OAuth discovery fix
- github-remote: Authorization server metadata endpoint returned 404
- intercom: Redirect URL not allowed
- kollektiv: Server shut down
- listenetic: OAuth completes but can't fetch tools
- meta-ads: Pending OAuth discovery fix
- neon-remote: Pending OAuth discovery fix
- netlify: No registration endpoint found
- plaid: DCR registration failed
- simplescraper: OAuth completes but tool fetch fails
- square: Redirect URL not allowed
- stytch: OAuth completes but broken session
- vercel: Redirect URL not allowed

Note: Local versions of atlassian, box, github, and neon are preserved as they are working.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: kgprs