exp push/pull: don't include baseline commit

[dberenbaum]

dvc exp push/pull transfer all cached outputs for all experiment commits up to and including the baseline commit on which the experiment is based. The baseline commit is a regular Git commit, so it might be unexpected that it's data is pushed/pulled by exp push/pull, and if no dvc.lock exists in the baseline commit, this will generate a warning that could be confusing.

@iesahin @pmrowla @daavoo

[pmrowla]

This should be simple to fix, we just need to remove
https://github.com/iterative/dvc/blob/049a856cd93c14e6a2efdbf6f5e02b028885a544/dvc/repo/experiments/utils.py#L90-L91