Delete NuGet.config and Dockerfile from spring cloud example

[kamperiadis]

Issue describing the changes in this PR

Remove obsolete MyGet references to make code-mirror pipeline pass Delete unnecessary Dockerfile from spring cloud example to make code-mirror pipeline pass

Pull request checklist

• [x] My changes do not require documentation changes
  • [ ] Otherwise: Documentation issue linked to PR
• [x] My changes should not be added to the release notes for the next release
  • [ ] Otherwise: I've added my notes to release_notes.md
• [x] My changes do not need to be backported to a previous version
  • [ ] Otherwise: Backport tracked by issue/PR #issue_or_pr
• [x] I have added all required tests (Unit tests, E2E tests)

Additional information

Additional PR information