failOnUnstable option

### Feature Request

Currently if a test fails the job status will be unstable. Would be great to able to set the job status to fail in these cases.
There can be an option which would fail the job in case of unstable behavior.

No files or tests are named. Start by locating the code that handles unstable test results and job status, then determine where a configurable option belongs. Done means an option can turn unstable results into a failed job while preserving the current behavior by default.

Written by the indexing model from the issue text.