ECBackend,ReplicatedPG: delete temp if we didn't get the transaction

We always send the transaction for operations on temp objects,
but if we didn't get the final transacition on the actual object,
we might end up failing to remove the temp object.  Thus, if
we get a sub op and don't have the transaction, just remove the
named temp objects.

Signed-off-by: Samuel Just <sam.just@inktank.com>
PGBackend/ECBackend: handle temp objects correctly

Signed-off-by: Samuel Just <sam.just@inktank.com>