fs_mgr_overlayfs: Fallback to allocate scratch on super if /data failed

b/255593675 showed that gsid can fail to allocate scratch on /data on
some device configurations. Before we can locate the root cause,
gracefully fallback to previous "scratch-on-super" logic in case of
error.

Bug: 255593675
Test: Presubmit
Test: manual test
Change-Id: I229ab51f11fa354a6f231c4d083dd6329d6a9579