Disable noncollectible alc finalization (dotnet/coreclr#21189)

Disable noncollectible alc finalization (dotnet/coreclr#21189)

* Disable noncollectible AssemblyLoadContext finalization

The constructor of AssemblyLoadContext was missing a call to
GC.SuppressFinalize for non-collectible AssemblyLoadContext. That means
that the finalizer can be executed and unloading being initialized even
for non-collectible AssemblyLoadContext.
This change fixes that.

* SuppressFinalize non-collectible AssemblyLoadContext

The finalizer for the non-collectible AssemblyLoadContext is never
called and so it should not be in the finalization queue.

* Handle finalizer call without constructor executed

Check if the constructor was executed before we run the finalizer code.

Commit migrated from https://github.com/dotnet/coreclr/commit/ac732ffb6d2ff4d2bec72ac5ca0785ace4ace20a