[release/6.0] Notify Reference Tracker runtime of disconnect at the right time (...

[release/6.0] Notify Reference Tracker runtime of disconnect at the right time (#58533)

* Notify Reference Tracker runtime of disconnect at the right time

Based on misunderstanding of SyncBlock clean-up modes the indication of
when an Native Object Wrapper was being collected was being done after
the wrapper's Finalizer was run. However, this information must be conveyed
prior to wrapper finalization and synchronously during the GC.

* Review feedback.

Co-authored-by: Aaron Robinson <arobins@microsoft.com>