Fix information flow about fingerprinting dotnet files in WBT

[ilonatommy]

Fixes #112814.

Tested on #112730. We were missing a correct flow of WasmFingerprintDotnetJs value in WBT. The test doesn't have to be disabled with this fix.

The logging that was commented out in the method that was failing was actually useful, I would keep it.

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (2)

src/mono/wasm/Wasm.Build.Tests/ProjectProviderBase.cs:122

• Uncommenting this debug logging line may clutter the test output during normal runs. Consider gating the logging behind a verbose condition or a flag to keep output clean by default.

_testOutput.WriteLine("Comparing {expectedFilename} with {actualFile}, expectFingerprintOnDotnetJs: {expectFingerprintOnDotnetJs}, expectFingerprint: {expectFingerprint}");

src/mono/wasm/Wasm.Build.Tests/Common/EnvironmentVariables.cs:26

• The environment variable key was changed from 'WASM_FINGERPRINT_DOTNET_JS' to 'USE_DOTNET_FINGERPRINTING_FOR_TESTS'; please ensure that all test configurations and dependent code are updated to reflect this change.

internal static readonly bool UseFingerprintingDotnetJS    = Environment.GetEnvironmentVariable("USE_DOTNET_FINGERPRINTING_FOR_TESTS") is "true";

[lewing]

did you mean to leave the test output line in the pr?

[ilonatommy]

Yes, I did. Do you think it's too noisy? If it was there, it would have shortened the investigation. I could also collect the text from 122 and print only in line 152, when we for sure throw.