Customization of Single Stat should allow change Colorized Thresholds independently on each other

Customization of Single Stat should allow change Colorized Thresholds independently on each other

Found and reproduced in: cloud2.influxdata.com

## Steps to Reproduce

1. Create a dashboard, an Single Stat chart (I used [influxdata/community-templates/raspberrypi](https://github.com/influxdata/community-templates/pull/191))
2. Customize Single Stat
3. Modify at least 5 Colorized Thresholds, each with a different value,
4. Save the graph and dashboard.
5. Open to edit the Single Stat again

## Current status

All values are same, inherit the highest entered threshold value. If you edit the value in one box, all the values in remaning thresholds change too. It is not possible to differentiate one threshold from another.


## Desired behavior

Behavior is a regression defect. The desired behavior is the ability to define thresholds independently