The default walking applier performs a real temporary mount for
unpacking, but the mount manager failed to adapt to the walking
differ.
This fixes the EROFS snapshotter together with the default walking
differ, otherwise it reports:
```
ctr: apply layer error for "[]": failed to extract layer sha256:[]:
failed to mount /var/lib/containerd/tmpmounts/containerd-mount3992073457:
internal mount option "X-containerd.mkfs.fs=ext4" was not consumed by
the mount manager
```
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
