Throttle metric writing by 3 seconds am: 32a73a96d1

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2363989

Change-Id: If5e8b4bc8c901bae088db29cf383d691afa86ee4
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>