Merge "Remove usage of base/string/* in libfs_avb" into main am: 752112003d

Original change: https://android-review.googlesource.com/c/platform/system/core/+/3265051

Change-Id: Iceb8689b1643eb1cdc2d4b6d118988bf1364da2c
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>