Add a speed limit feature to simulate slow network am: 46a860c0b6

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2237257

Change-Id: I5fd99d17e7b2105c414e7d1e008d77116c527b79
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>