Cleanup shell magic in 00-setup-introduction

[figaw]

The task "Task: Inject sidecar for the age service" in 00-setup-introduction doesn't really add anything istio-wise to the exercise, it's more of an inline-text-editing trick.

If you know that you can cat a manifest to kubectl apply -f - and you know that grep -v can strip lines from the input, it should be "obvious" that.. you can strip the annotation.

If you don't know these things, an istio course might not be the right place to add it?

The continuation of the exercise also isn't using that we re-add the proxy.

Please discuss.