don't upload test results, when commit statuses are disabled

[prakashsurya]

It's possible to manually start a test run via the Jenkins UI, and have commit status be disabled. If this occurs, the test results are still uploaded to Manta, polluting the results contained in a directory for any given commit or pull request.

As an example, one might see that a PR was triggered for testing only a single time, but then see multiple test results for the PR when looking at that PR's directory in Manta. This could be confusing, and it wouldn't be easy to know which of the multiple test iterations is what is linked in the GitHub commit statuses for the PR.

Due to this possible confusion, and the fact that the results have limited to no value when commit statuses are disabled, we should just avoid uploading the results when tests are manually triggered in this fashion.