TCK: @Additional, @Stochastic annotations should be used by the TCK runtime

[ktoso]

Currently the annotations in https://github.com/reactive-streams/reactive-streams/blob/master/tck/src/main/java/org/reactivestreams/tck/Annotations.java are just a more visible way to document which method is testing an optional rule and which not. They do not actually influence the runtime (behaviour of failing or skipping a test - depending on if it's optional).

We can make these annotations preserved for the runtime, and then we can remove the additional versions of subscriberTest vs. optionalSubscriberTest etc. So it's one less place to get a missmatch between documentation and the actual behaviour of the TCK.

[viktorklang]

I vote for removing those annotations instead, and make the name of the spec methods more signal this intent. Then if we want to change from additional to required, or from notVerified to additional, we introduce a new method name and deprecate the old.

[ktoso]

I like this idea since it's more discoverable from the logs etc - and users will also see that "notVerified_spec23232_sdfsdfsdf SKIPPED" so it makes more sense. A nice +1 from me :)
I also like how it makes things more obvious when we deprecate something (hello "post-1.0-land")

[smaldini]

that is quite clever and easy win :)

[smaldini]

note for ref, @viktorklang comment on #189
Renamed "unverified" to "untested" (same length as "optional" and "required") Changed ___ to _

[viktorklang]

Fixed! :)