[influxdb v2 - beta10] Need deterministic colors applied per series

I have 2 hosts that I'm pinging, and I chart the max and min separately.

For some reason Chronograph inverts the colors applied within each cell, and I cannot figure out why.

It would appear that colouring is based on some internal key ID, instead of a controllable user definition. Ie. the same host, should always be the same colour in my use case.

use cases:
- per category / identity
- per statistic (eg. median, 95th, 99th percentile)

**Example1 - colors inverted plotting the same two hosts in separate cells:**


```
#For cell1 showing max response times

from(bucket: "test123")
|> range(start: v.timeRangeStart, stop: v.timeRangeStop)
|> filter(fn: (r) => r["_measurement"] == "ping")
|> filter(fn: (r) => r["url"] == "167.x.x.x" or r["url"] == "192.168.0.1")
|> filter(fn: (r) => r["_field"] == "maximum_response_ms")

#For cell showing min response times:

from(bucket: "test123")
|> range(start: v.timeRangeStart, stop: v.timeRangeStop)
|> filter(fn: (r) => r["_measurement"] == "ping")
|> filter(fn: (r) => r["url"] == "167.x.x.x" or r["url"] == "192.168.0.1")
|> filter(fn: (r) => r["_field"] == "minimum_response_ms")

```

**Example2 - for a Min/Median/Max, the colours applied per statistic change on each refresh of the cell**


```
from(bucket: "test123")
|> range(start: v.timeRangeStart, stop: v.timeRangeStop)
|> filter(fn: (r) => r["host"] == "host1")
|> filter(fn: (r) => r["_measurement"] == "conntrack_value")
|> filter(fn: (r) => r["_field"] == "value")
|> filter(fn: (r) => r["type"] == "percent")
|> aggregateWindow(every: v.windowPeriod, fn: max)
|> yield(name: "max")

from(bucket: "test123")
|> range(start: v.timeRangeStart, stop: v.timeRangeStop)
|> filter(fn: (r) => r["host"] == "host1")
|> filter(fn: (r) => r["_measurement"] == "conntrack_value")
|> filter(fn: (r) => r["_field"] == "value")
|> filter(fn: (r) => r["type"] == "percent")
|> aggregateWindow(every: v.windowPeriod, fn: min)
|> yield(name: "min")

from(bucket: "test123")
|> range(start: v.timeRangeStart, stop: v.timeRangeStop)
|> filter(fn: (r) => r["host"] == "host1")
|> filter(fn: (r) => r["_measurement"] == "conntrack_value")
|> filter(fn: (r) => r["_field"] == "value")
|> filter(fn: (r) => r["type"] == "percent")
|> aggregateWindow(every: v.windowPeriod, fn: median)
|> yield(name: "median")
```

Start by reproducing the color changes with the two-host and min/median/max query examples in the issue, then trace the series-color assignment entry point used by Chronograf. Done means a host or statistic keeps the same controllable color across cells and refreshes.

Written by the indexing model from the issue text.