[3.0.x] Remove telemetry examples

[mkurz]

So there is no way to test these examples because we don't have credentials to the lightbend repos.

And... it seems it is not supported anymore by lightbend anyway:
If you google:

• https://www.google.com/search?q=%22cinnamon.play.http%22
  

you come to a page which gives you 404:

• https://developer.lightbend.com/docs/telemetry/current//instrumentations/play/play-configuration.html

Google cache still has the page. It was about telemetry Play integration:

• http://webcache.googleusercontent.com/search?q=cache%3Ahttps%3A%2F%2Fdeveloper.lightbend.com%2Fdocs%2Ftelemetry%2Fcurrent%2F%2Finstrumentations%2Fplay%2Fplay-configuration.html

But this integration does not exist anymore now:

• https://developer.lightbend.com/docs/telemetry/current//instrumentations/instrumentations.html