Time limit regression suite run, so it captures stacks and zap reports before github job cancellation

The smoketest github action is set to timeout if the regression suite jobs are taking too long, e.g. because they're stalled.
However, we want to capture the stacks and zap reports of in-flight queries before that happens.

Time limit the regression suite run, so that it is signalled and provokes a graceful exit - in order to capture stacks and zap reports.