Modify StatsCompanionService event processing thread am: a8ea5e90c4

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

Change-Id: I728ebb8eab44933fda10dfc0d955a287c2756cc8
Signed-off-by: Automerger Merge Worker <[email protected]>