Investigate why NETStandard.Library package dependency is being added to net461 dependency groups for some of our packages

[joperezr]

I hit this when doing my changes for #39099 by adding configurations and noticed that some of our Microsoft.Extensions packages had this dependency added for the net461 group. We'll have to investigate why that is happening and fix whatever is causing it.

cc: @ericstj

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[ViktorHofer]

dup of #39641