Fix MODULES-9914: physical_volumes provisioning with 'followsymlinks'

[CharlieR-o-o-t]

This commit fixes broken physical device provisioning in case of symlink usage.
Jira issue: https://tickets.puppetlabs.com/browse/MODULES-9914

With 'followsymlinks' enabled we should have correct set of physical volumes (should, is) in order to compare it, and apply action.

Error example:
err /Stage[main]/Lvm/Lvm::Volume_group[vg1]/Volume_group[vg1]/physical_volumes change from ['/dev/sdb'] to ['/dev/disk/by-id/scsi-0QEMU_QEMU_HARDDISK_3243ac35-a879-4c26-b', '/dev/disk/by-id/scsi-0QEMU_QEMU_HARDDISK_0e99e7db-b97d-4017-a'] failed: Could not remove physical volume /dev/sdb from volume group 'vg1'; this physical volume may be in use and may require a manual data migration (using pvmove) before it can be removed (Execution of '/usr/sbin/vgreduce vg1 /dev/sdb' returned 5: Physical volume "/dev/sdb" still in use)

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