Add ISTIO Template

We have the ability to install telegraf in a way that will forward istio metrics to InfluxDB. SRE has already created some useful dashboards from this data.

I have created some tasks and an additional bucket, and some dashboards that operate on that data. Left to do:
[ ] Add latency metrics to the bucket
[ ] Add alerts for errors and latency

I will need help creating the actual template, and I have no familiarity with the Telegraf config.

Review the existing Telegraf configuration, the additional bucket, and the dashboards already created for Istio metrics. Determine how latency metrics and error and latency alerts are represented in the community template, then verify that the resulting template operates on the stated data.

Written by the indexing model from the issue text.