Set Fsverity props conditionally

Only system and system_ext kati partitions have fsverity metadata.
system_ext also does not use etc/* pattern.
`fsverity-metadata-targets-patterns` in build/make/core/Makefile
contains all the patterns.

Test: Ran the diff test on system, system_ext and vendor locally
Change-Id: Id8cc3a06fc8d5663dea18c00f0a4f289d82d46b8