redhat: disable kunit by default
KUNIT has some slight overhead even when not being run. Upstream has made some strides on removing and isolating this overhead. One of these ways is completely disable kunit and only enabling it at boot time via a cmdline arg kunit.enable=1.
Default kunit to being disabled, and enable it manually or via CI when appropriate.
Signed-off-by: Nico Pache npache@redhat.com