Support PriorityQueue as a feature gate.

[mcbenjemaa]

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PriorityQueue is a new feature in controller-runtime. We added a corresponding feature gate to Cluster API to allow testing before priority queue eventually (likely) becomes the only queue implementation in CR.

Anything else you would like to add:
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Ref:

• Feature: Priority Queue kubernetes-sigs/controller-runtime#2374
• Feature: PriorityQueue kubernetes-sigs/cluster-api#11704

Environment:

• Cluster-api-provider-proxmox version:
• Kubernetes version: (use kubectl version):
• OS (e.g. from /etc/os-release):