disk: skip read xattr for files other than block device

[huww98]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

should reduce false warnings about unable to read xattr

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

time="2024-08-06T20:34:04+08:00" level=warning msg="getVolumeCount: failed to get xattr of core, assuming not managed by us: operation not supported"
time="2024-08-06T20:34:04+08:00" level=warning msg="getVolumeCount: failed to get xattr of fd, assuming not managed by us: operation not supported"
time="2024-08-06T20:34:04+08:00" level=warning msg="getVolumeCount: failed to get xattr of initctl, assuming not managed by us: no such file or directory"
time="2024-08-06T20:34:04+08:00" level=warning msg="getVolumeCount: failed to get xattr of log, assuming not managed by us: no such file or directory"
time="2024-08-06T20:34:04+08:00" level=warning msg="getVolumeCount: failed to get xattr of stderr, assuming not managed by us: operation not supported"
time="2024-08-06T20:34:04+08:00" level=warning msg="getVolumeCount: failed to get xattr of stdout, assuming not managed by us: operation not supported"

Does this PR introduce a user-facing change?

NONE

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

[mowangdk]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: huww98, mowangdk

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