Fix annotations links using github.com even for GHES

There are few locations were github.com is hardcoded, making it incompatible with github enterprise servers that are hosted on other domains.
From what I understood from these code lines, they are only cosmetic (sent as annotations in deployments).

https://github.com/Azure/k8s-deploy/blob/507f2d4fc713cdc92f96880e350464687ce2e960/src/utilities/workflowAnnotationUtils.ts#L24
https://github.com/Azure/k8s-deploy/blob/ca8d2604acf262265b6640fc4de4e060effbb555/src/utilities/githubUtils.ts#L47

There is `GITHUB_SERVER_URL` env var and [some others](https://docs.github.com/en/enterprise-server@2.22/actions/learn-github-actions/environment-variables) to get the server domain.