feat: Add proxy-busy-buffers-size to NIC

[AlexFenlon]

Proposed changes

• Add proxy-busy-buffers-size to ConfigMap
• Add nginx.org/proxy-busy-buffers-size to Ingress Annotations
• Add busy-buffers-size to VirtualServer
• Update Ingress-nginx shared annotations to include nginx.org/proxy-busy-buffers-size

NIC PR: nginx/kubernetes-ingress#8088

Checklist

Before sharing this pull request, I completed the following checklist:

• I read the Contributing guidelines
• My branch adheres to the Git conventions
• My content changes adhere to the F5 NGINX Documentation style guide
• If my changes involve potentially sensitive information¹, I have assessed the possible impact
• I have waited to ensure my changes pass tests, and addressed any discovered issues

Footnotes

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