sample_smc conversion of sample stats to idata can result in warning

[ricardoV94]

Description

Sometimes we have less sample stats than chains with SMC (the concept of draws is hacked a bit), and this line here will trigger an arviz warning: https://github.com/pymc-devs/pymc/blob/cc902124ed08fe8c3007699451cc0c16f38520d2/pymc/smc/sampling.py#L266-L270

Reported by an user in https://discourse.pymc.io/t/incorrect-number-of-draws-in-smc-example/17119/2

We should suppress that warning, (perhaps in all internal uses of dict_do_dataset by PyMC)?

CC @aloctavodia @OriolAbril