Fix missing checkout step in several pipelines (dotnet/coreclr#26773)

Fix missing checkout step in several pipelines (dotnet/coreclr#26773)

I have apparently missed some of the pipelines in my "one checkout"
change. I have gone over all yml files under eng/pipelines and
fixed the four remaining yml files by adding the missing step.

Thanks

Tomas

Commit migrated from https://github.com/dotnet/coreclr/commit/16b27f7852a223752601f4623abae5c82ca732a1