Remove the example provider

[fabriziopandini]

As per #3985 (comment), the example provider was required for some old e2e, but given that those have been removed we can now safely delete the example provider.

• remove cmd/example-provider
• remove make docker-build-example-provider target

/kind cleanup

[fabriziopandini]

/milestone v0.4.0

/help
/good-first-issue

[k8s-ci-robot]

@fabriziopandini:
This request has been marked as suitable for new contributors.

Please ensure the request meets the requirements listed here.

If this request no longer meets these requirements, the label can be removed
by commenting with the /remove-good-first-issue command.

In response to this:

/milestone v0.4.0

/help
/good-first-issue

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[sheetalsingala]

Can I give this a try?

[vincepri]

Go for it @sheetalsingala !

[arghya88]

/assign @sheetalsingala
/lifecycle active