Fix InvalidCastExceptions from RCW reuse #833
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Scottj1s
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AaronRobinsonMSFT
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manodasanW
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This reverts commit 3f5dd34.
manodasanW
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We were seeing InvalidCastExceptions because after the native pointer is released, we are still getting old RCW back from the .NET cache if that same pointer is encountered again due to .NET thinks it is still alive. This is due to the cache cleanup happens after finalization of the RCW which isn't at the same time as when the object reference in the RCW releases the final ref on the pointer. In .NET 6, there would be a new API for us to use to clear the cache, but until then we are putting in a mitigation for .NET 5.
IObjectReferences which are associated with an RCW are not immediately finalized but their finalization is deferred twice in an attempt to get its finalization to happen in gen 2 which means the RCW finalization and cache cleanup in gen 2 will be done by that time.
Fixes #762