Optimize .NET version detection and improve output formatting

[MitchellCash]

• Implementing caching for system information to avoid redundant calls
• Using more efficient string concatenation and table operations
• Optimizing loops with early exits and local variable caching
• Improving version notes formatting to clearly indicate LTS and fix the incorrect marking of some releases as not-secure instead of security patches
  • From: v8.0.15 (not-secure, 2025-04-08) [dotnet-sdk-osx-arm64.tar.gz v8.0.408]
  • To: v8.0.15 (LTS - Security Patch) [SDK v8.0.408]

[Copilot]

Pull Request Overview

This PR optimizes .NET version detection by implementing caching and performance improvements while fixing version notes formatting to properly display LTS status and security patches.

• Implemented system information caching to avoid redundant calls during execution
• Replaced string.format with more efficient string concatenation operations
• Fixed version notes to properly show LTS status and security patches instead of confusing "not-secure" labels

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