Modify StatsCompanionService event processing thread am: a8ea5e90c4

Original change: https://android-review.googlesource.com/c/platform/packages/modules/StatsD/+/2969313

Change-Id: I7659b355d87591ffdc11e0daf83554ac5c7f689c
Signed-off-by: Automerger Merge Worker <[email protected]>