psh_utils: Update ServiceSingleton code

The new code handles service death.

Flag: EXEMPT Bugfix
Test: atest service_singleton_tests
Test: power stats show when enabled, after stats service killed
Test: atest powerstats_collector_tests
Test: atest audio_powerstats_benchmark
Test: atest audio_token_benchmark
Test: atest audio_powerstatscollector_benchmark
Bug: 350114693
Change-Id: I0783b3c58ed8412b363b613127873f01ef8d6737