[APM] Bug: Set minimum scale to 1% for the Transaction error rate chart

[formgeist]

Kibana version: master

Summary

The current transaction error rate chart has the y-axis scale set to 100% but this is not ideal, as the error rate can possibly hide critical information such as a slight but significant increase in error rate because it's fixed to 100%.

Solution

I propose the set a minimum scale of 1% and otherwise let the y-axis be set to max value for the given time range.

[elasticmachine]

Pinging @elastic/apm-ui (Team:apm)