Add some tracing for release fences

* Fix FenceMonitor to cleanly teardown
* App-side tracing for BBQ release callbacks
* Trace future compleition in TxnCallbackInvoker

Bug: 360932099
Bug: 357762453
Flag: EXEMPT debugging
Test: builds
Test: perfetto
Change-Id: I188c04da1e249b672b428837c328568d9e7a1e66