Azure Spot Virtual Machines: Try to restore functionality now generally available

Spot VM Try to restore benefits: * Attempts to restore Azure Spot Virtual Machines evicted due to capacity. * Restored Azure Spot Virtual Machines are expected to run for a longer duration with a lower probability of a capacity triggered eviction. * Improves the lifespan of an Azure Spot Virtual Machine, so workloads run for a longer duration. * Helps Virtual Machine Scale Sets to maintain the target count for Azure Spot Virtual Machines, similar to maintain target count feature that already exist for Pay-As-You-Go VMs. Try to restore is disabled in scale sets that use [Autoscale](https://review.docs.microsoft.com/en-us/azure/virtual-machine-scale-sets/virtual-machine-scale-sets-autoscale-overview). The number of VMs in the scale set is driven by the autoscale rules.  [Learn more](https://docs.microsoft.com/en-us/azure/virtual-machine-scale-sets/use-spot#try--restore). * Azure Spot Virtual Machines * Features * [ Azure Spot Virtual Machines](https://azure.microsoft.com/en-gb/products/virtual-machines/spot/)