Halve test erofs image size am: 6fb5303589 am: 1a9bea81ff am: 0180efb3f5

Original change: https://android-review.googlesource.com/c/platform/system/update_engine/+/2234809

Change-Id: I2c9b6e1aab5f6c7829d963d27e323755663763a0
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>