storage: compute reflink path at run

Path needs to be recomputed when called because it may
change when revisions_to_keep is changed

Author: Guiiix

qubes/storage/reflink.py

@@ -176,9 +176,10 @@ def __init__(self, *args, **kwargs):
         self._path_precache = self._path_vid + "-precache.img"
         self._path_dirty = self._path_vid + "-dirty.img"
         self._path_import = self._path_vid + "-import.img"
-        self.path = (
-            self._path_clean if self.snapshots_disabled else self._path_dirty
-        )
+
+    @property
+    def path(self):
+        return self._path_clean if self.snapshots_disabled else self._path_dirty
 
     @contextmanager
     def _update_precache(self):