Remove group by auto from Kapacitor alert rule builder

[jaredscheib]

[jaredscheib]

[jaredscheib]

That error comes up and it's not clear what the problem is from the error message. But it's because auto is the default setting, and one would not think to turn off auto. Also, template variables aren't implemented for Kapacitor alert queries. So it makes creating an alert obscurely error out without any indication that it's due to auto unless you look at the console.

[jaredscheib]

@nathanielc says there's no reason to have auto GROUP BY for Kapacitor alerts, and that it would be confusing.

I'll remove it.