kunit: Rename KUNIT_ASSERT_FAILURE to KUNIT_FAIL_AND_ABORT for readability

Both KUNIT_FAIL and KUNIT_ASSERT_FAILURE defined to KUNIT_FAIL_ASSERTION
with different tpye of kunit_assert_type. The current naming of
KUNIT_ASSERT_FAILURE and KUNIT_FAIL_ASSERTION is confusing due to their
similarities. To improve readability and symmetry, renames
KUNIT_ASSERT_FAILURE to KUNIT_FAIL_AND_ABORT. Makes the naming
consistent, with KUNIT_FAIL and KUNIT_FAIL_AND_ABORT being symmetrical.
Additionally, an explanation for KUNIT_FAIL_AND_ABORT has been added to
clarify its usage.

Signed-off-by: Eric Chan <ericchancf@google.com>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>