Remove references to previous repo path

[zrhoffman]

This PR

• replaces github.com/Comcast/traffic_control with github.com/apache/trafficcontrol
• replaces NotComcast with Kabletown
• Makes the ATC git pre-commit hooks work again

---

Which Traffic Control components are affected by this PR?

• pre-commit hooks
• Traffic Control Cache Config (integration test env file)
• Automation (build system README, infrastructure/docker, env files)

What is the best way to verify this PR?

1. Follow the instructions at /misc/git/README.md to add the ATC pre-commit hook:
   https://github.com/apache/trafficcontrol/blob/a56b5ec035ab4e21efd08fd530affbf70223715b/misc/git/README.md#L31
2. Try to add a commit:

   git commit --allow-empty --allow-empty-message --no-edit

The hooks should pass.

PR submission checklist

• This PR has tests
• This PR has documentation
• A changelog entry is unnecessary
• This PR DOES NOT FIX A SERIOUS SECURITY VULNERABILITY (see the Apache Software Foundation's security guidelines for details)