ceph-volume: refresh lvm metadata cache

When running rhel8 containers on a rhel7 host, after zapping an OSD
there's a discrepancy with the lvmetad cache that needs to be refreshed.
Otherwise, the host still sees the lv and can makes the user confused.
If user tries to redeploy an OSD, it will fail because the LV isn't
present and need to be recreated.

ie:

```
 stderr: lsblk: ceph-block-8/block-8: not a block device
 stderr: blkid: error: ceph-block-8/block-8: No such file or directory
 stderr: Unknown device, --name=, --path=, or absolute path in /dev/ or /sys expected.
usage: ceph-volume lvm prepare [-h] --data DATA [--data-size DATA_SIZE]
                               [--data-slots DATA_SLOTS] [--filestore]
                               [--journal JOURNAL]
                               [--journal-size JOURNAL_SIZE] [--bluestore]
                               [--block.db BLOCK_DB]
                               [--block.db-size BLOCK_DB_SIZE]
                               [--block.db-slots BLOCK_DB_SLOTS]
                               [--block.wal BLOCK_WAL]
                               [--block.wal-size BLOCK_WAL_SIZE]
                               [--block.wal-slots BLOCK_WAL_SLOTS]
                               [--osd-id OSD_ID] [--osd-fsid OSD_FSID]
                               [--cluster-fsid CLUSTER_FSID]
                               [--crush-device-class CRUSH_DEVICE_CLASS]
                               [--dmcrypt] [--no-systemd]
ceph-volume lvm prepare: error: Unable to proceed with non-existing device: ceph-block-8/block-8
```

Closes: https://bugzilla.redhat.com/show_bug.cgi?id=1886534

Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>

library/ceph_volume.py

@@ -656,6 +656,8 @@ def run_module():
         if any(skip) or module.params.get('osd_fsid', None):
             rc, cmd, out, err = exec_command(
                 module, cmd)
+            for scan_cmd in ['vgscan', 'lvscan']:
+                module.run_command([scan_cmd, '--cache'])
         else:
             out = 'Skipped, nothing to zap'
             err = ''