Replace references to likely malicious container registry with ghcr

[jsoref]

Description

https://bmitch.net/blog/2025-08-22-ghrc-appears-malicious/

Fixes #{issue}

Change Details

Check all that apply:

• New feature
• Bug fix
• Non-code change
• Non-breaking change
• Breaking change
• Requires a documentation change

Release Note

How Has This Been Tested?

Describe any testing done to verify changes. Provide enough detail that tests can be reproduced.

Checklist:

• My code follows the Contribution and Style guidelines of this project
• My changes generate no new warnings
• New and existing unit tests pass locally with my changes
• I have added test details that prove my fix is effective or that my feature works

[jsoref]

I can't check off:

My code follows the Contribution and Style guidelines of this project

As that link is broken. It probably should be to https://github.com/vmware-tanzu/build-tooling-for-integrations/blob/main/CONTRIBUTING.md