Chaos type #2: Simulate EBS failure

Force-detach EBS volumes, to simulate a catastrophic EBS failure.  Typically the instances continue to run, but all I/O to the EBS volumes block forever.  Sort of similar to the behaviour seen in total EBS failures.

"Sadly" we can't detach the root EBS volume, so this is only applicable when there's a non-root EBS volume attached.  But the strategy auto-detects whether that is the case, and just removes itself from the applicable list if it can't be applied.

Force-detaching EBS volumes is quite likely to cause data corruption, so don't use this on production data where you don't have a good backup.  But if you're stress testing a database on test data, it's not a bad one to try out!