Minor APM dump improvements

- print system usages as enum strings;
- indicate that the 'id' of the communication strategy is
  printed;
- add accidentally removed "is soundtrigger" flag to
  RecordClientDescriptor.

Bug: 205884982
Test: adb shell dumpsys media.audio_policy
Change-Id: Iccb847c971864e4781ccc92cbf078303ef35d51b