Allow vendor-init-settable to persist.sys.zram_enabled

persist.sys.zram_enabled is set in vendor/build.prop in taimen and walleye,
which was added after the initial whitelist.
go/treble-sysprop-compatibility requires whitelisting such a property to
allow it to be overridden by vendor/{default|build}.prop.

Bug: 73905119
Test: succeeded building and test with taimen
Change-Id: I931182aa05eb90c14df6e2c7cc26913f3874fa18