[app-layout] Drawer toggle primary variant middle line appearance on Windows

[web-padawan]

Description

Finding from #10738

The middle line in the drawer toggle variant differs in color from other lines.

Expected outcome

Expected the primary variant to look the same on Windows as it does on Mac OS.
Note: seems to also apply to base styles where a different --_vaadin-icon-menu is used.

Minimal reproducible example

Use dev/app-layout.html page with base styles and Aura on Windows.

Steps to reproduce

See above.

Environment

Vaadin version(s): 25
OS: Windows

Browsers

No response