framework: remove external frameworks support

Kirk supports the execution of certain kselftests and liburing
testing suites. It was initially created as an experiment but it's
largely unused and we really don't want to maintain code that has to be
adapted according to each new framework feature.

Reviewed-by: Li Wang <liwang@redhat.com>
Acked-by: Petr Vorel <pvorel@suse.cz>
Acked-by: Cyril Hrubis <chrubis@suse.cz>
Acked-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>

Author: acerv