Fix --only filter silently matching zero tests with multiple UUIDs

The subset check required ALL passed UUIDs to match a single test
case's trace, which is impossible since each case has one UUID.
With 2+ failed tests, the CI retry selected 0 tests and exited 0,
silently masking real failures. Changed to intersection so each
case is kept if ANY of the passed UUIDs matches.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: sbryngelson

toolchain/mfc/test/test.py

@@ -71,7 +71,7 @@ def __filter(cases_) -> typing.List[TestCase]:
 
             checkCase = case.trace.split(" -> ")
             checkCase.append(case.get_uuid())
-            if not set(ARG("only")).issubset(set(checkCase)):
+            if not set(ARG("only")).intersection(set(checkCase)):
                 cases.remove(case)
                 skipped_cases.append(case)