Fix and stabilize vm selftests results before including in CI

This merge request introduces the ability to run vm kselftests with different "groups" of tests.

This will be utilized by our CI to isolate each test and test/report them individually. Also backport some changes to the gup_test that allows for better reporting.

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2089501

Signed-off-by: Nico Pache npache@redhat.com