kunit: tool: Don't overwrite test status based on subtest counts

kunit: tool: Don't overwrite test status based on subtest counts

If a subtest itself reports success, but the outer testcase fails,
the whole testcase should be reported as a failure. However the status
is recalculated based on the test counts, overwriting the outer test
result. Synthesize a failed test in this case to make sure the failure
is not swallowed.

Link: https://lore.kernel.org/r/20251230-kunit-nested-failure-v1-2-98cfbeb87823@linutronix.de
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>