NLB-7074: Update docs to add standardv3 plan for azure

[Naveen-Gopu-F5]

Proposed changes

• Updated docs to use standardv3 as default plan instead of standardv2 in NginxaaS Azure.
• Updated the NCU definition based on this new standardv3 plan
• Updated the usage and cost estimator for standardv3 plan.

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

1. Potentially sensitive information includes personally identify information (PII), authentication credentials, and live URLs. Refer to the style guide for guidance about placeholder content. ↩

[github-actions]

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