Remote EC2 hosts which are not accessible via ssh should fail with system error

When a remote EC2 instance is "crashed" by the powercycle test it sometimes fails to become available via ssh. The AWS status still indicates it as "running". The work in SERVER-34996 is intended to help analyze why this may occur.

The following should be done such that we can distinguish between a test failure (possible data corruption) and an environment failure:

• powertest.py should exit with a way to indicate it failed due to ssh
• If the exit is due to ssh, then a system failure should be triggered (which will show the task as purple)

In order to help find out why a particular EC2 instance is failing to permit ssh we should also do the following:

• Termination of the EC2 instance should not be attempted if a system failure occurred due to ssh issue from powercycle (for non-Windows variants)
• Increase the expire_hours to 24 (for non-Windows variants)