Permanent errors don't cause job failure

[jlewi]

If a container crashes with an exit code of 1 this should be considered a permanent error and cause the job to fail.

This doesn't happen because
isRetryableTerminationState
https://github.com/jlewi/mlkube.io/blob/master/pkg/trainer/training.go

Requires that a termination message be set in order for the exit code to be trusted.
This is legacy code that is no longer applicable. It assumes we were using a launcher.sh script which users aren't.

We should get rid of that check.