Checkpoints on tiered tables are disallowed.  See the code in __checkpoint_name_check, which disallows "tiered:" objects from being allowed for named checkpoints. We should be able to support it, as we can put the named checkpoint in the top level file associated with the tiered table.

Once this is fixed, I hope we can remove the "test_checkpoint.test_checkpoint" line from hook_tiered.py, and thus run "run.py --hook tiered checkpoint22".  There's also a FIXME in test format.  Resolving that will allow test/format to run named checkpoints with tiered storage.