AKS: Remove incorrect pattern for adminUsername and adminPassword in ManagedClusterWindowsProfile since 2019-04-01

[AbelHu]

Remove incorrect pattern for adminUsername and adminPassword in ManagedClusterWindowsProfile since 2019-04-01

https://docs.microsoft.com/en-us/rest/api/compute/virtualmachinescalesets/createorupdate#virtualmachinescalesetosprofile

    "ManagedClusterWindowsProfile": {
      "properties": {
        "adminUsername": {
          "type": "string",
          "description": "The administrator username to use for Windows VMs.",
          "pattern": "^[a-zA-Z0-9]+([._]?[a-zA-Z0-9]+)*$"
        },
        "adminPassword": {
          "type": "string",
          "description": "The administrator password to use for Windows VMs.",
          "pattern": "^(?=.*[a-z])(?=.*[A-Z])(?=.*[!@#$%\\^&\\*\\(\\)])[a-zA-Z\\d!@#$%\\^&\\*\\(\\)]{12,123}$"
        }
      },
      "required": [
        "adminUsername"
      ],
      "description": "Profile for Windows VMs in the container service cluster."
    },

[ghost]

Thanks for the feedback! We are routing this to the appropriate team for follow-up. cc @Azure/aks-pm.