azure-arm 2.5.1 incorrectly sets disablePasswordAuthentication false

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#### Overview of the Issue

When I set communicator=ssh and provide ssh_username and ssh_private_key_file but no password, the VM has properties.osProfile.linuxConfiguration.disablePasswordAuthentication set to false, but it should be true. When I use 2.5.0, I see the correct value (true)

#### Reproduction Steps

In the 'source "azure-arm"' block, set:
communicator = "ssh"
ssh_username = "..."
ssh_private_key_file = "..."

Do not set ssh_password

While packer runs, do a GET on the VM and observe properties.osProfile.linuxConfiguration

### Plugin and Packer version

packer: 1.14.3
plugin: github.com/hashicorp/azure v2.5.1

### Simplified Packer Buildfile

packer {
required_plugins {
azure = {
version = ">= 2.5.1"
source = "github.com/hashicorp/azure"
}
}
}

variable "venv_root" {
type = string
}

source "azure-arm" "prelim" {
os_type = "Linux"

polling_duration_timeout = "30m"

disk_caching_type = "ReadOnly"

communicator = "ssh"
ssh_username = "packer"
ssh_private_key_file = "/mnt/vss/_work/_temp/ssh-for-packer/id_rsa"

azure_tags = {
CopyFlag = "CopyV2"
hyperVversion = "2"
owner = "tester"
# https://developer.hashicorp.com/packer/docs/templates/hcl_templates/functions/datetime/formatdate
time_create = formatdate("YYYY-MM-DD hh:mm:ssZZZZ", timestamp())
}

# additional settings snipped - not relevant
}

build {
sources = ["sources.azure-arm.prelim"]

provisioner "shell" {
inline = [
"sudo mkdir -p /tmp/prelim",
"sudo chmod 777 /tmp/prelim",
]
}
# further provisioners snipped for brevity
}

### Operating system and Environment details

OS: Linux Ubuntu 20 (Canonical ESM)
Azure VM

### Log Fragments and crash.log files

n/a