automation: make regex search replace the default campaign

Created by: rvantonder

Stacked on #7790.

Proposal: make regex the default campaign selection. Why? New users are being introduced to a potentially unfamiliar concept with "campaigns", and definitely a new UI. Regex is a broadly familiar concept, so let's reduce the "newness" exposure and not throw them too far into the deep end. On first exposure users should not initially feel obliged to figure out what comby is in addition to the the campaign workflow/UI.