Consider running prebuilt detection on failing builds

[ViktorHofer]

In the case of dotnet/runtime#98006 prebuilt detection didn't run because the build failed. What's interesting about this PR is that it failed because it used the actual packages and not the SBRP ones for Microsoft.Build.Tasks.Core/17.8.3 and Microsoft.Build.Tasks.Core/17.8.3 but SBRPs for Microsoft.Build/17.8.3 and its dependencies.

The mix of SBRP and real packages for MSBuild wasn't obvious from the failing source-build leg. It failed with a very cryptic error which I wasn't able to diagnose. Kudos to @ericstj who found the actual problem.

As the source-build leg didn't log prebuilt errors, I didn't consider that SBRPs are still missing. I wonder if it would make sense to always run prebuilt detection, even when a build fails. Alternatively, should prebuilt detection run after restore instead of after the entire build?

[MichaelSimons]

Alternatively, should prebuilt detection run after restore instead of after the entire build?

Generally speaking restore is not the only way prebuilts are introduced. Installer in particular has many ways in which assets are pulled in outside of retore that get flagged by prebuilt detection.

[MichaelSimons]

Closing as repo level prebuilt detection is being removed with #5034.