Support of oms_agent_enabled add-on

[jchenDevops]

Describe your changes

Option to enable or disable OMS agent(Azure Monitor) add-on

Issue number

#600

Checklist before requesting a review

• The pr title can be used to describe what this pr did in CHANGELOG.md file
• I have executed pre-commit on my machine
• I have passed pr-check on my machine

Thanks for your cooperation!

[jchenDevops]

@microsoft-github-policy-service agree [company="Signal 1 AI"]

[jchenDevops]

@microsoft-github-policy-service agree company="Signal 1 AI"

[lonegunmanb]

Hi @jchenDevops thanks for opening this pr to us! I have a question for this pr, why don't set var.log_analytics_workspace_enabled to false if you don't want oms_agent?

[jchenDevops]

Hi @lonegunmanb,
If set var.log_analytics_workspace_enabled to false, defender cannot be enabled.
https://github.com/Azure/terraform-azurerm-aks/blob/main/main.tf#L462-L468