FIx initial background of main window

Co-authored-by: Fedor Indutny <79877362+indutny-signal@users.noreply.github.com>

app/main.main.ts

@@ -692,7 +692,7 @@ async function createWindow() {
     systemTraySettingCache.get(),
     isTestEnvironment(getEnvironment())
       ? '#ffffff' // Tests should always be rendered on a white background
-      : getBackgroundColor({ signalColors: true }),
+      : getBackgroundColor(),
     getSpellCheckSetting(),
   ]);