System.Collections.Immutable aren't runnable with trimming

[MichalStrehovsky]

#107872 added reflection to the test that cannot be statically analyzed. Native AOT outerloop testing has been on the floor ever since. I'm going to disable running all S.C.Immutable tests under native AOT on this issue to get outerloop green again.

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/area-system-collections
See info in area-owners.md if you want to be subscribed.

[eiriktsarpalis]

I think it should be fine to just disable the tests using reflection in Native AOT. They're there to validate certain non-functional invariants (e.g. whether the internal tree structures are always balanced) that we don't need to run on every platform (and ideally should be replaced with debug asserts at some point).

[lambdageek]

This might be a good place to use [UnsafeAccessor] instead of reflection

[MichalStrehovsky]

I think it should be fine to just disable the tests using reflection in Native AOT

The tests could also be annotated for trimming.

This might be a good place to use [UnsafeAccessor] instead of reflection

If we don't have to run these tests on Framework, it might. But I do see $(NetFrameworkMinimum) in the csproj.