Description:
The menu panel that opens when clicking the Bookmarks button in the sidebar header has different colors for the horizontal separators and menu item hovered state when using generated themes as opposed to privileged themes.

Steps to reproduce:

1. Prepare two instances of Nightly with new profiles
2. Access about:config on both and set extensions.experiments.enable to true
3. Restart the browsers to apply the above pref
4. Load a pair of the same generated and privileged theme in the browsers via about:debugging
5. Open the sidebar via the CTRL+B keyboard shortcut
6. Click the “Bookmarks” button at the top of the sidebar panel to reveal the options menu
7. Observe the difference in color for the horizontal separators
8. Hover over the menu items and observe the hovered state color

Actual:
Generated themes horizontal separators and menu item hovered state colors are different from the ones used by the privileged theme.

Expected:
Generated themes horizontal separators and menu item hovered state colors should be the same as the ones used by the privileged theme.

The affected generated themes are (all of them):

independent-voices – activist-balanced-colorway
independent-voices – activist-bold-colorway
independent-voices – activist-soft-colorway
independent-voices – dreamer-balanced-colorway
independent-voices – dreamer-bold-colorway
independent-voices – dreamer-soft-colorway
independent-voices – expressionist-balanced-colorway
independent-voices – expressionist-bold-colorway
independent-voices – expressionist-soft-colorway
independent-voices – innovator-balanced-colorway
independent-voices – innovator-bold-colorway
independent-voices – innovator-soft-colorway
independent-voices – playmaker-balanced-colorway
independent-voices – playmaker-bold-colorway
independent-voices – playmaker-soft-colorway
independent-voices – visionary-balanced-colorway
independent-voices – visionary-bold-colorway
independent-voices – visionary-soft-colorway
life-in-color—abstract-balanced-colorway
life-in-color—abstract-bold-colorway
life-in-color—abstract-soft-colorway
life-in-color—cheers-balanced-colorway
life-in-color—cheers-bold-colorway
life-in-color—cheers-soft-colorway
life-in-color—elemental-balanced-colorway
life-in-color—elemental-bold-colorway
life-in-color—elemental-soft-colorway
life-in-color—foto-balanced-colorway
life-in-color—foto-bold-colorway
life-in-color—foto-soft-colorway
life-in-color—graffiti-balanced-colorway
life-in-color—graffiti-bold-colorway
life-in-color—graffiti-soft-colorway
life-in-color—lush-balanced-colorway
life-in-color—lush-bold-colorway
life-in-color—lush-soft-colorway
true-colors—2022blue-colorway
true-colors—2022green-colorway
true-colors—2022orange-colorway
true-colors—2022purple-colorway
true-colors—2022red-colorway
true-colors—2022yellow-colorway

This is the same as bug 1808882 and bug 1808890.