Restore the check of fs-verity status

IncFs v1 does not support fs-verity. The original condition before
ag/20327155 allowed a split to be installed without .fsv_sig, but ag/
ag/20327155 changes the expectation. To maintain the behavior, still
check the fs-verity-ness in addition.

Bug: 257775576
Test: abtd
Change-Id: If0a87b2ef4ad2e4c4920dbd17d1591b021f470d1