Backport "stop testing with nodejs" to net9

[ilonatommy]

Backport #108582 to release/9.0-staging.

To reduce WASM test matrix

• remove pipelines
• remove WasmTestOnNodeJS scenario
• remove node based Wasm.Build.Tests tests
• Old Blazor_net50 project that was added in [wasm] Don't use workload for tfm < net6.0 #56606 to be used in WBT but we started using different logic to test Blazor since then and it can be safely removed.

Leave untouched:

• PlatformDetection.IsNotNodeJS
  • HTTP & WS tests
  • Hybrid globalization tests
• detection in `src\mono\browser\test-main.js
• any production code

Contributes to #111753.

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