Collect Log Files for Failures

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Collecting and uploading all logs for all tests takes a while and generates really big log files. We should only upload log files for failures. That means we would need to be able to collect logs for specific test cases, determine if the test passes or fails, and delete the log file if it passed.

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With the PowerShell test script, logs for success cases are no longer generated. But since all the tests are run in one big batch, if any tests fail, we keep all the logs. Running each test individually, with its own log takes too long. Perhaps, in the future I can figure out a way to speed it up, but for now, this will have to do.