Traces are not exported when a process is terminated immediately after a test finishes

[NomadBlacky]

Sometimes, such as when running test commands directly from sbt, the process may exit after the test finishes but before sending the telemetry data.

# worked (run test in sbt shell)
$ sbt
> test

# did not work (run test directly in terminal)
$ sbt test

Implement exporting telemetry data explicitly by the reporter when the test ends.