Enable delegate marshalling for collectible types (dotnet/coreclr#20158)

Enable delegate marshalling for collectible types (dotnet/coreclr#20158)

* Enable delegate marshalling for collectible types

This change is trivial - it just removes checks preventing the delegate
marshalling for collectible types. The unmanaged to managed thunks are
allocated from a global LoaderAllocator and they are released when the
corresponding managed delegates are collected. So for unloadability, we
don't need to change this behavior in any way.

* Disable CoreFX tests outdated by the change

Commit migrated from https://github.com/dotnet/coreclr/commit/49209e181103006603e2cf4e05dccb564bef537d