Table: Some color schemes do not work with Sparkline Cell

### What happened? When using Sparkline Cell in Table, many of the color schemes either don't work or do not work like you would expect they should. ### What did you expect to happen? When selecting red-yellow-green, for example, we'd expect that the scheme would use more of the range of red yellow green, but most of the visualizations shown will be all one color. <img width="1621" height="381" alt="Image" src="https://github.com/user-attachments/assets/1846b6f8-d801-4c77-af0f-0f607b1ca40b" /> For "Reds (by value)" or other "by value" color schemes, the visualizations can almost completely vanish due to transparency. <img width="1614" height="409" alt="Image" src="https://github.com/user-attachments/assets/e3ec5e80-ae2a-41b0-bdae-402aefe5dd79" /> ### Did this work before? No ### How do we reproduce it? 1. Use the Sparklines table gdev dashboard 2. Edit one of the panels 3. Change the color scheme ### Is the bug inside a dashboard panel? _No response_ ### Environment (with versions)? _No response_ ### Grafana platform? None ### Datasource(s)? _No response_