* testing-common refactoring: replace direct AgentTestRunner usage with spock spec
* Updated instrumentation docs
* Fix reactor-core library tests
ReactorCoreTest was getting a tracer from GlobalOpenTelemetry before LibraryTestTrait had a change to initialize the SDK
* Remove outdated doc
* Remove unnecessary dependencies
* Formatting
* Rename TRACER to tracer
* Move WrappedFuture to top-level class
* Add missing shadow config
* Use simpler type
* Use simpler base class