Clean up obsolete net7 test conditionals while preserving Classic compatibility

[Copilot]

The codebase contained framework-conditional branches that no longer affect currently targeted test frameworks, but some shared runtime files are also compiled by KubernetesClient.Classic (netstandard2.0;net48) and must keep their guards.

This PR now focuses on safe dead-code cleanup without breaking Classic.

• Framework-conditional cleanup in tests

  • Removed obsolete #if NET7_0_OR_GREATER wrappers in:
    • tests/KubernetesClient.Tests/KubernetesJsonTests.cs
    • tests/KubernetesClient.Tests/KubernetesYamlTests.cs
  • Assertions now reflect current test target frameworks without unnecessary preprocessor branching.

• Classic compatibility correction (follow-up feedback)

  • Restored required framework guards in shared runtime files:
    • src/KubernetesClient/KubernetesJson.cs
    • src/KubernetesClient/Models/V1Status.ObjectView.cs
    • src/KubernetesClient/Watcher.cs
  • This keeps KubernetesClient.Classic buildable while retaining the test-side cleanup.

• Validation

  • Built KubernetesClient.Classic successfully.
  • Ran targeted Classic tests (SimpleTests) successfully.
  • Re-ran focused KubernetesClient.Tests JSON/YAML datetime tests successfully.

> [!WARNING]
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Original prompt

Could you please help to clean up dead code that no longer target in build?
e.g. net6 specific code

---

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[k8s-ci-robot]

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[tg123]

@copilot will Classic work?

[Copilot]

@copilot will Classic work?

Yes — Classic still works after the latest fix. I restored the required framework guards in the shared files compiled by KubernetesClient.Classic and validated with dotnet build src/KubernetesClient.Classic/KubernetesClient.Classic.csproj plus dotnet test tests/KubernetesClient.Classic.Tests/KubernetesClient.Classic.Tests.csproj --framework net8.0 --filter "FullyQualifiedName~SimpleTests" (pass). Commit: 9e6b357.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• crl.comodoca.com
  • Triggering command: /home/REDACTED/work/csharp/.codeql-scratch/dbs/csharp/working/.dotnet/dotnet /home/REDACTED/work/csharp/.codeql-scratch/dbs/csharp/working/.dotnet/dotnet restore --no-dependencies /home/REDACTED/work/csharp/csharp/src/KubernetesClient.Classic/KubernetesClient.Classic.csproj --packages /home/REDACTED/work/csharp/.codeql-scratch/dbs/csharp/working/packages /p:DisableImplicitNuGetFallbackFolder=true --verbosity normal /p:TargetFrameworkRootPath=/home/REDACTED/work/csharp/.codeql-scratch/dbs/csharp/working/emptyFakeDotnetRoot /p:NetCoreTargetingPackRoot=/home/REDACTED/work/csharp/.codeql-scratch/dbs/csharp/working/emptyFakeDotnetRoot /p:AllowMissingPrunePackageData=true (dns block)
• ocsp.comodoca.com
  • Triggering command: /home/REDACTED/work/csharp/.codeql-scratch/dbs/csharp/working/.dotnet/dotnet /home/REDACTED/work/csharp/.codeql-scratch/dbs/csharp/working/.dotnet/dotnet restore --no-dependencies /home/REDACTED/work/csharp/csharp/src/KubernetesClient.Classic/KubernetesClient.Classic.csproj --packages /home/REDACTED/work/csharp/.codeql-scratch/dbs/csharp/working/packages /p:DisableImplicitNuGetFallbackFolder=true --verbosity normal /p:TargetFrameworkRootPath=/home/REDACTED/work/csharp/.codeql-scratch/dbs/csharp/working/emptyFakeDotnetRoot /p:NetCoreTargetingPackRoot=/home/REDACTED/work/csharp/.codeql-scratch/dbs/csharp/working/emptyFakeDotnetRoot /p:AllowMissingPrunePackageData=true (dns block)

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