checkpoint_gc: Abort gc if no progress detected

If a device is undergoing heavy data usage, we will not make any
forwards progress in this script, leading to running for the full
timeout length. In that case, we can rely on garbage collecting during
the next boot.

Bug: 291181976
Test: Run checkpoint_gc while running fsstress
Change-Id: I568a78afe6189271772ff7d11edb78ab34a5d9ea
1 file changed