Reland "Do not create 4-byte sequences in `ConvertUtf16ToModifiedUtf8()`" am: 15ddcab869

Original change: https://android-review.googlesource.com/c/platform/art/+/1762227

Change-Id: I8b6cc527173d670f9b30aefcf67ecfa057b57929
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>