Add missing AnnotationsAdaptersTest test

* Adds back AnnotationsAdaptersTest (it was misspelt as AnnotationsAdapterTest because of which manual-unit.php failed)
* Makes sure that TestClass is included only once (it is required by both AnnotationsAdapterTest and AnnotationsTest)
* Allows one to use config.db.local.php for local tests (the file is gitignore'd and won't be committed by accident to the tree)