Revert "NEXUS-5971: alternative solution that mimics the original scanning 'is repository type a declared interface of the implementation' check at runtime"

This reverts commit 305c7886079da4c2ca57802a18e4e4aa11164de0.
Revert "NEXUS-5971: prefer non-group repositories over group repositories (as some repositories like P2 use the same hint for both non-group and group repositories and don't restrict visibility with @Typed)"

This reverts commit 68ed44a171534fd028db193ab775177af0de19b8.
Revert "NEXUS-5971: widen SimpleRepositoryImpl binding so it can be seen by the mediator (could also have added Repository.class to @Typed)"

This reverts commit bf565d357d2d67bfd451f37d6f98387f67ad7a93.
NEXUS-5971: restore @RepositoryType scanning approach (simplified)