While working on #69118 I noticed that library linker tests aren't running in CI at all. The step successfully terminates after the projects are restored but not executed.

Example build: https://dev.azure.com/dnceng/public/_build/results?buildId=1757179&view=logs&j=eb951b81-6f9f-5627-0593-6e7e925eb8a5&t=55619121-b736-513e-b9cc-23d0fc111be3.

I'm investigating this right now locally.

cc @joperezr @dotnet/area-infrastructure-libraries