Use stable objects for callbacks

Fixes a memory leak contributing to b/419430883.

In Android's Runtime, method references are not stable across callsites.

Concretely If you register (this::fun) and unregister (this::fun), this
may lead to twice as much fun as you bargained for. The lambda instances
generated for register and unregister are NOT equal!

This leads to memory leaks as the registration works but the
deregistration is not recognised, leading to everlasting fun.

Bug: 419430883
Test: atest WMShellUnitTests # sufficiently large to trigger the leak
Flag: android.tracing.client_side_proto_logging
Change-Id: Idc478fdf60985d86144e9ec317b198a038f60b1e