init: flush ext4 file system on shutdown

Previously, only f2fs /data filesystems were shutdown using the
F2FS_IOC_SHUTDOWN ioctl. This change adds support for shutting down ext4
/data filesystem with the EXT4_IOC_SHUTDOWN ioctl.

Bug: 403381187
Test: Verify /data was clean after reboot on desktop
Test: Verify e2fsck returns immediately when booting on desktop

Change-Id: I08208888d839649efe54fcab5d73177e9e06ec88