Make generate-compiler-code fail if CompilersIOperationGenerator encounters a problem

[jcouv]

Fixes #75603

Validated that the correctness legs fail in CI prior to fixing the xml comment in IOperationInterfaces.xml:

========================== Starting Command Output ===========================
...
Running CompilersIOperationGenerator.csproj "D:\a\_work\1\s\src\Compilers\Core\Portable\Operations\OperationInterfaces.xml" "D:\a\_work\1\s\artifacts\log\Release\Generated\Core\Operations"
D:\a\_work\1\s\.dotnet\dotnet.exe run --project D:\a\_work\1\s\src\Tools\Source\CompilerGeneratorTools\Source\IOperationGenerator\CompilersIOperationGenerator.csproj --framework net9.0 "D:\a\_work\1\s\src\Compilers\Core\Portable\Operations\OperationInterfaces.xml" "D:\a\_work\1\s\artifacts\log\Release\Generated\Core\Operations"
�]9;4;3;�\�]9;4;0;�\IConditionalOperation.IsRef does not have correctly formatted comments, please ensure that there is a <summary> block for the property.
Encountered xml errors, not generating
Command failed to execute with exit code 1: D:\a\_work\1\s\.dotnet\dotnet.exe run --project D:\a\_work\1\s\src\Tools\Source\CompilerGeneratorTools\Source\IOperationGenerator\CompilersIOperationGenerator.csproj --framework net9.0 "D:\a\_work\1\s\src\Compilers\Core\Portable\Operations\OperationInterfaces.xml" "D:\a\_work\1\s\artifacts\log\Release\Generated\Core\Operations"
##[error]PowerShell exited with code '1'.
Finishing: Generate Syntax Files

[jaredpar]

Ouch ...