shared/cfg/subtests.cfg.sample: Remove JeOS from some variants

In some cases, the test variant is irrelevant, in others,
JeOS lacks a toolchain for it to work. So, let's remove
them and leave a more meaningful list of tests for
people interested in JeOS.
Signed-off-by: NLucas Meneghel Rodrigues <lmr@redhat.com>