Drop the expired entries in NetworkEvents table regularly. am: 2fc47b291f

Original change: https://android-review.googlesource.com/c/platform/packages/modules/NetworkStack/+/3252336

Change-Id: Ib6a18cc36a0cdd07ebafdbb16842fbb864490b26
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>