[BUG] don't require access rules for manila shares

[kayrus]

Describe the bug

Currently velero returns an error, when creating a share/snapshot from a volume that doesn't have access rules

Steps to reproduce the behavior

Create a manila snapshot from the share with no access rules

Expected behavior

velero shouldn't fail, when the source share doesn't have access rules

Used versions

• Velero version(velero version): -
• Plugin version(kubectl describe pod velero-...): master
• Kubernetes version(kubectl version): -
• Openstack version: -