remove appveyor (#5413)
remove appveyor (#5413)

AppVeyor has been more detrimental than actually helpful with regards to CI testing:

- Users are unable to re-build their own failing PRs. A project admin has to rebuild the PR
- The project somehow mixes up bacongobbler/helm with Helm/helm when observing CI status
- The only contributors able to test legitimate Windows failures lands on the shoulders of contributors with Windows devices

This removes Appveyor from Helm 3 testing until we can figure out a better solution.

Signed-off-by: Matthew Fisher <d7b4933872ff6976310344046643071159afa913@microsoft.com>
adamreese/deployment-manager,adamreese/helm,michelleN/deployment-manager,helm/helm,bacongobbler/helm,michelleN/deployment-manager,michelleN/deployment-manager,adamreese/deployment-manager,michelleN/deployment-manager,adamreese/deployment-manager,bacongobbler/helm,adamreese/deployment-manager,adamreese/helm,adamreese/deployment-manager,helm/helm