storage/reflink: update snap_on_start volume size in start()
storage/reflink: update snap_on_start volume size in start()

QubesOS/qubes-core-admin,QubesOS/qubes-core-admin,marmarek/qubes-core-admin,marmarek/qubes-core-admin,QubesOS/qubes-core-admin,marmarek/qubes-core-admin