Add UnfulfillableCapacity and InsufficientCapacity in the list of EC2…

[hanwen-cluster]

… error codes used for fast fail-over

According to https://docs.aws.amazon.com/AWSEC2/latest/APIReference/errors-overview.html

UnfulfillableCapacity: At this time there isn't enough spare capacity to fulfill your request for Spot Instances. You can wait a few minutes to see whether capacity becomes available for your request. Alternatively, create a more flexible request. For example, include additional instance types, include additional Availability Zones, or use the capacity-optimized allocation strategy.

InsufficientCapacity: There is not enough capacity to fulfill your import instance request. You can wait for additional capacity to become available.

Checklist

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