report_go_test does not fail when there are no tests

[chizhg]

When the test package does not contain any tests, the report_go_test function reports as success the test flow still passes even when there is error.

https://knative.slack.com/archives/CA1DTGZ2N/p1589561963210900 is the discussion on Slack.

[chaodaiG]

There are two sides of this problem:

1. There are cases where a test suite crashed and no junit result logged, this is where report_go_test reports a test failure
2. When there is no go test in a directory, report_go_test still reports it as failed, this is not desired. However, I would argue that it should report failure if someone call go test <dirA> and there is no test in <dirA>

[github-actions]

This issue is stale because it has been open for 90 days with no
activity. It will automatically close after 30 more days of
inactivity. Reopen the issue with /reopen.Mark the issue as
fresh by adding the comment /remove-lifecycle stale.

[chizhg]

/lifecycle frozen