Fix: prevent snapshotter from deleting in-use devices during snapshot removal

[Aaron-ding-coder]

What this PR does / why we need it:
When using a Kata runtime, the OverlayFS mount is performed in a different namespace, making it invisible from the host environment. However, when performing unmount and device detachment, the snapshotter checks if the host has any mounts using this device and will continue device detachment if it detects no host-level mounts.

In this case, during UnmountAndDetachBlockDevice, checkOverlaybdInUse will return "not in use," even though this snapshot is actually being used by another active snapshot.

Therefore, when we perform unmount and device detach, we should check the DB to see whether an active snapshot is using this device. If true, we shouldn't unmount or detach the block device, because this will cause active containers to lose access to their filesystems.

Please check the following list:

• Does the affected code have corresponding tests, e.g. unit test, E2E test?
• Does this change require a documentation update?
• Does this introduce breaking changes that would require an announcement or bumping the major version?
• Do all new files have an appropriate license header?

[BigVan]

LGTM