remove ENABLE_CDN_TESTING and places that use it

[SgtPooki]

we should remove ENABLE_CDN_TESTING dealbot should be testing SPs, not services that wrap SPs

we should also remove all the CDN testing code in the codebase.. I don't think this will come back

[BigLep]

If there isn't a usecase to test "CDN datasets" then I agree we can remove it.

[BigLep]

This is a subtask under #158 as we should do this work as part of having a clean/tight/solid "data storage' check.