Remove xz_chromeos.cc am: e68e13045e am: fd9ff36554

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/3304584

Change-Id: Icb151ee4bb7795e99eedde2e68db0d2407e41538
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>