[Maps] Color ramp UI for percent of a top term in join layer is broken

[jsanz]

Kibana version:
8.0.0-rc1 (tested in 7.16.2 and it works)

Elasticsearch version:
same

Server OS version:
cloud

Browser version:
Firefox 95

Browser OS version:
Ubuntu 20.04

Original install method (e.g. download page, yum, from source, etc.):
Cloud

Describe the bug:
The color ramp for the percent of a top term metric in a joined field of a Choropleth layer does not work.

Steps to reproduce:

1. Create a Choropleth Map with EMS countries and Kibana sample flights
2. Add a new metric for the Carrier (Top Term)
3. Change fill color to percent of top Carrier
4. The color ramp is not shown (but the data is rendered by a default color ramp)

Expected behavior:

A color ramp displays the percent of the top term.

Screenshots (if relevant):

Errors in browser console (if relevant):

No errors in Browser console

Provide logs and/or server output (if relevant):

Any additional context:

[jsanz]

I can also get the same error for the Label color and Label border color properties. For the Label size the list does not show the metric.

[nreese]

Regression caused by #116366