Low priority vmss test and help update. (Azure#7882)

Updated help text and test location for low priority vmss

Author: adewaleo

src/command_modules/azure-cli-vm/azure/cli/command_modules/vm/_params.py

@@ -314,7 +314,7 @@ def load_arguments(self, _):
         c.argument('vm_sku', help='Size of VMs in the scale set. Default to "Standard_DS1_v2". See https://azure.microsoft.com/en-us/pricing/details/virtual-machines/ for size info.')
         c.argument('nsg', help='Name or ID of an existing Network Security Group.', arg_group='Network')
         c.argument('priority', resource_type=ResourceType.MGMT_COMPUTE, min_api='2017-12-01', arg_type=get_enum_type(VMPriorityTypes, default=None),
-                   help="(PREVIEW) Priority. Use 'Low' to run short-lived workloads in a cost-effective way")
+                   help="Priority. Use 'Low' to run short-lived workloads in a cost-effective way")
         c.argument('eviction_policy', resource_type=ResourceType.MGMT_COMPUTE, min_api='2017-12-01', arg_type=get_enum_type(VirtualMachineEvictionPolicyTypes, default=None),
                    help="(PREVIEW) The eviction policy for virtual machines in a low priority scale set.")
         c.argument('application_security_groups', resource_type=ResourceType.MGMT_COMPUTE, min_api='2018-06-01', nargs='+', options_list=['--asgs'], help='Space-separated list of existing application security groups to associate with the VM.', arg_group='Network', validator=validate_asg_names_or_ids)