Remove hba-only directories in clear_existing()
Remove hba-only directories in clear_existing()

rtslib never creates hba directories without a storage object within it,
but if under some circumstance these existed then clear_existing() wouldn't
remove them, since StorageObject::all()'s glob ignores them.

Add code to ensure these are also removed.

Signed-off-by: Andy Grover <b7d524d2f5cc5aebadb6b92b08d3ab26911cde33@redhat.com>

cvubrugier/rtslib-fb