fstest: replacing fs_mgr_read_fstab() with fs_mgr_read_fstab_default()

The original default /fstab.{ro.hardware} might be moved to
/vendor/etc/. or /odm/etc/. Use the new API to get the default
fstab instead of using the hard-coded /fstab.{ro.hardware}.

Bug: 35811655
Test: boot sailfish
Change-Id: Ie11a4f22ed449ef90cbcc7117227a99ea9d79110
1 file changed