[Feature] Native Resource Exclusions for AKS Recommended Prometheus Alerts (Label-Based Opt-Out)

**Is your feature request related to a problem? Please describe.**
Yes. Azure recommended AKS Prometheus alerts currently do not provide a built-in, first-class exclusion behavior for specific Kubernetes resources.
In real operations, teams often need to suppress known-noisy workloads, non-production namespaces, or specific PVC scenarios without disabling recommended alerts globally or forking all alert rules.

Today, to get this behavior, operators must:
- Clone or override recommended alert rule groups
- Add custom PromQL exclusion clauses
- Ensure kube-state-metrics label collection is configured correctly
- Maintain these customizations over time as Microsoft updates baseline recommended rules

This creates drift, adds operational risk, and makes recommended alerts harder to adopt at scale.

**Describe the solution you'd like**
Add native exclusion support to Azure recommended AKS alerts, so customers can safely opt out specific resources without replacing the full rule set.

Requested behavior:
- Support a standard exclusion label convention for Kubernetes objects, for example:
- key: excluded_from_alerts
- value: true
- Apply this across relevant recommended alert scopes where dimensions exist:
- pod-scoped alerts
- namespace-scoped alerts
- PVC-scoped alerts
- Expose exclusion behavior as a supported configuration option in Azure:
- AKS/Monitor onboarding settings
- CLI and ARM/Bicep
- Portal experience
- Ensure Microsoft-managed recommended rule updates preserve this exclusion behavior automatically.
- Document exactly which recommended alerts support exclusions and at which scope.

**Describe alternatives you've considered**
- Customizing Prometheus rule groups manually with PromQL unless clauses.
- Deploying and maintaining custom rule templates instead of Microsoft recommended defaults.
- Disabling noisy alerts entirely, which reduces coverage and signal quality.
- Namespace-level alert routing/suppression downstream in action handling systems rather than at rule-evaluation level.

All alternatives increase maintenance burden and can break when recommended rule baselines evolve.

**Additional context**
This is especially valuable for enterprise AKS environments with:
- Shared clusters (prod and non-prod workloads)
- Temporary test workloads
- Platform teams managing many clusters with centralized standards

A native exclusion capability would improve adoption of recommended alerts, reduce customization drift, and preserve signal quality while still allowing practical suppression for known exceptions.