Enable Batch writes for OTA installation.

By default set `ro.virtual_ab.compression.threads` it to false.
Enabling this will improve OTA install time at the cost
of one more CPU.

Bug: 254188450
Test: OTA on Pixel
Change-Id: Idf1fa950a5fc394f0d783d80c84045295185fb85
Signed-off-by: Akilesh Kailash <akailash@google.com>