[Darwin] MTRDevice should tear down subscription on dealloc (#37418)

* [Darwin] MTRDevice should tear down subscription on dealloc

* Update src/darwin/Framework/CHIP/MTRDevice_Concrete.mm

Co-authored-by: Boris Zbarsky <bzbarsky@apple.com>

* Update src/darwin/Framework/CHIP/MTRDevice_Concrete.mm

Co-authored-by: Boris Zbarsky <bzbarsky@apple.com>

* Fix log line.

* Make sure that _persistClusterData only notifies delegates when persistence actually happens.

* Fix unit test to wait for delete properly

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Co-authored-by: Boris Zbarsky <bzbarsky@apple.com>
Co-authored-by: Justin Wood <woody@apple.com>

Author: 3 people