Remove libchrome stringprintf.h functions am: 11c3da63da am: 9ecd0dced8

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/3316555

Change-Id: Ibfa0ffd4826c49554508c5040bb38ec5719372be
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>