Do not change extension entries colors based on devtools theme

Before this CL we were using colors from devtools palette. Some of these, where taken from theme tokens, which vary depending on devtools theme. This was not the initially intended behavior, as colors tend to have a meaning, so we don't want them to change based on the UI colors (e.g. we don't want "primary" colors to look red if devtools theme color is red). Instead what we want are the colors of the default theme, regardless of the theme devtools has.

Bug: 358307050
Change-Id: Ic4bb5a3216d19aedaba6d6aafce2c891372e7dda
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/5961601
Reviewed-by: Jack Franklin <jacktfranklin@chromium.org>
Commit-Queue: Jack Franklin <jacktfranklin@chromium.org>
Auto-Submit: Andres Olivares <andoli@chromium.org>