Breeze Dark theme must be darkened

[ArtyIF]

Tested versions

• Reproducible in any version with Breeze Dark theme

System information

Godot v4.5.beta1 - Arch Linux #1 ZEN SMP PREEMPT_DYNAMIC Tue, 10 Jun 2025 21:32:14 +0000 on Wayland - X11 display driver, Multi-window, 1 monitor - Vulkan (Forward+) - dedicated AMD Radeon RX 570 Series (RADV POLARIS10) - AMD Ryzen 7 5700X 8-Core Processor (16 threads) - 31.24 GiB memory

Issue description

KDE/breeze@9c13ba3 made the Breeze Dark theme darker for KDE Plasma's 6.4 release. I think this should also be reflected in Godot, since I use this theme to bring the editor more in-line with the rest of my desktop.

I'd update the theme and make the PR myself, but I'm not even sure what specific color has been chosen for the base color, and how the brightness of it was changed.

Steps to reproduce

1. Open editor
2. Select Breeze Dark theme
3. Compare

Minimal reproduction project (MRP)

N/A