Some tests cause stracktraces to be printed even on successful runs, e.g.:

• jstests/noPassthrough/tassert_failpoint.js
• jstests/noPassthrough/exit_logging.js

It seems wasteful to spend time on symbolizing such stacktraces, so we should skip symbolizing on test success and also cleanup stracktrace files, so that they don't confuse resmoke when it runs the next tests.