Error codes regression for validating signatures

[shishirx34]

It looks like the change: https://github.com/NuGet/NuGet.Client/pull/2391/files#diff-c6fa634239b1e7654fa549386f77ed3cL206 introduced regressions. The earlier route would return NU3028, however, this change is returning NU3018 error codes.

@PatoBeltran knows the context.

This change has broken NuGet/NuGet.Jobs SignatureValidatorIntegrationTests It expects the logged messages to contain

NU3028: The author primary signature's timestamp found a chain building issue: The revocation function was unable to check revocation because the revocation server was offline.

However, actual logged messages are something like:

Signed package TestSigned.leaf 1.1.0 passed format verification for validation 2eb974b0-8103-48b4-892e-d805052da1a0. Errors: Warnings: \r\nNo repository signatures needed removal from package TestSigned.leaf 1.1.0 for validation 2eb974b0-8103-48b4-892e-d805052da1a0.\r\nSigned package TestSigned.leaf 1.1.0 passed full signature integrity and trust verification for validation 2eb974b0-8103-48b4-892e-d805052da1a0. Errors: Warnings: NU3018: The author primary signature's timestamp found a chain building issue: The revocation function was unable to check revocation because the revocation server could not be reached. For more information, visit ., NU3018: The author primary signature's timestamp found a chain building issue: The revocation function was unable to check revocation for the certificate.\r\nAuthor signed package TestSigned.leaf 1.1.0 for validation 2eb974b0-8103-48b4-892e-d805052da1a0 is valid with certificate fingerprint:

Also, following tests are broken due to same issues:
https://github.com/NuGet/NuGet.Jobs/blob/352ce8d5a2306ce735703e2fa2bc48ebe82ce24b/tests/Validation.PackageSigning.ProcessSignature.Tests/SignatureValidatorIntegrationTests.cs#L363
https://github.com/NuGet/NuGet.Jobs/blob/352ce8d5a2306ce735703e2fa2bc48ebe82ce24b/tests/Validation.PackageSigning.ProcessSignature.Tests/SignatureValidatorIntegrationTests.cs#L1452
https://github.com/NuGet/NuGet.Jobs/blob/352ce8d5a2306ce735703e2fa2bc48ebe82ce24b/tests/Validation.PackageSigning.ProcessSignature.Tests/SignatureValidatorIntegrationTests.cs#L1511

[PatoBeltran]

Merged in 4.9.0-rtm and dev