[automerger skipped] cleanup - read_config() and ipv4_local_prefixlen am: 8452f3f652 am: e529ea9ab7 -s ours

am skip reason: Change-Id I67b70fe298f69ac51dfbc5daf4078b842fb62808 with SHA-1 8452f3f652 is in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/android-clat/+/11736257

Change-Id: Ib75fbb56e4e0880f4222792fdee31b092366cc0a