Only skip checkpointing for freshly formatted ext4

"Do not reboot with commit failure when ext4 userdata is wiped" has
caused a regression in cuttlefish on f2fs. Overlay.img rapidly grows to
the full userdata size. This updates that CL to only affect partitions
marked for block based checkpointing.

Test: Boot Cuttlefish, monitor overlay.img for 5 minutes
Bug: 285019395
Change-Id: I7d8634e6535ee1531a0df9fb51c6f9c410cbfe92