The marker panel should use the colors of the markers in the timeline

Currently in the marker panel all the markers are drawn using the same blue, but on the timeline some markers have a different color.

I think re-using the timeline marker colors in the marker panel would help with consistency and discoverability (because when looking in the marker panel, the name of the markers are visible, so seeing the names next to the colors would help people learn the meaning of the colors).

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-119)