VMTemplate builder - add max virtual machines limit configuration support

[alwaysharsha]

• Added maxVirtualMachinesLimit field to AzureVMTemplateFluent with getter and setter methods
• Updated AzureVMTemplateBuilder to propagate maxVirtualMachinesLimit during template construction
• Modified build() method to conditionally set the limit on AzureVMAgentTemplate when provided

Testing done

Submitter checklist

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• Ensure you have provided tests that demonstrate the feature works or the issue is fixed

[timja]

Please fill out testing done, to demonstrate that you've tested it and it does what you need.