Fixes DefaultProjectIcon scaling with editor scale

Should fix #27009 where the DefaultProjectIcon was scaling
with the EDSCALE. Now it checks if the icon name is equal
to "DefaultProjectIcon" and sets the scale to 1.0 instead of
EDSCALE.

(cherry picked from commit 740100d671f37db47dd15a3b6109225c17a0c4c6)

editor/editor_themes.cpp

@@ -226,8 +226,15 @@ void editor_register_and_generate_icons(Ref<Theme> p_theme, bool p_dark_theme =
 	// Generate icons.
 	if (!p_only_thumbs) {
 		for (int i = 0; i < editor_icons_count; i++) {
+			float icon_scale = EDSCALE;
+
+			// Always keep the DefaultProjectIcon at the default size
+			if (strcmp(editor_icons_names[i], "DefaultProjectIcon") == 0) {
+				icon_scale = 1.0f;
+			}
+
 			const int is_exception = exceptions.has(editor_icons_names[i]);
-			const Ref<ImageTexture> icon = editor_generate_icon(i, !is_exception);
+			const Ref<ImageTexture> icon = editor_generate_icon(i, !is_exception, icon_scale);
 
 			p_theme->set_icon(editor_icons_names[i], "EditorIcons", icon);
 		}