Colour by _colour doesn't actually work in scatter charts unless the data is ordered by _colour

Nobody has claimed this yet.

__Steps to reproduce:__
List the minimal actions needed to reproduce the behavior.

1. Make a scatter chart of data where _value is plotted against _time
2. group() your data (which also muddles up order a bit)
3. Create a _colour field using map() so that _colour is a copy of _value
4. sort() your data by "_time"
5. select "fill by" _colour

__Expected behavior:__
You are of course expecting that it colours ("fills") the points by _colour (i.e. the _value).
like this

It doesn't. Not if you look closely at the bottom right point.

__Actual behavior:__
It sets the colour of the points according to a weird combination of _time or possibly the order that the points appear in the table.

You can prove that the colouring is related to the sort order by keeping **everything else the same** and just sorting by "_colour" instead of by "_time"
That gives the correct result.

The bug has maybe gone un-noticed because in many cases the order of the rows might be something like the fill by value

__Environment info:__
* InfluxDB cloud 2.0 interface.
* Creation of dashboard cell
* scatter plot

Start by reproducing the issue in an InfluxDB Cloud dashboard cell using a scatter plot, following the listed group, map, sort, and fill-by steps. Trace how point colours are assigned when rows are sorted by _time versus _colour; done means fill-by _colour produces the same correct colours regardless of row order.

Written by the indexing model from the issue text.