Revert "ANDROID: incremental-fs: remove index and incomplete dir on umount"

This reverts commit fe0c18d0.

This is follow up cleanup after revert of:
"Revert "ANDROID: incremental-fs: fix mount_fs issue"

Bug: 220805927

Signed-off-by: Tadeusz Struk <tadeusz.struk@linaro.org>
Change-Id: I7749401484d87b9d519bd7b9600cd02f91a18090