Fix for Not Grouped By on Table View

[georgeke]

Remove the default metrics field on Table View since using the Not Grouped By field requires the metrics field to be empty. This would cause a Choose either fields to [Group By] and [Metrics] or [Columns], not both error.

[coveralls]

Coverage increased (+0.02%) to 82.127% when pulling fcc9bde on georgeke:not-grouped-by into 087c47a on airbnb:master.

[mistercrunch]

Let's handle all cases here (label and description as well) and remove that logic from the templates if that's possible.

[coveralls]

Coverage decreased (-0.2%) to 81.942% when pulling 73bafbf on georgeke:not-grouped-by into 087c47a on airbnb:master.

[coveralls]

Coverage decreased (-0.01%) to 82.095% when pulling 14c8729 on georgeke:not-grouped-by into 087c47a on airbnb:master.

[mistercrunch]