use info notice for color mode change notification toast (elastic#205364

)

## Summary

This PR changes the toast notification for instances when the color mode
changes from a toast that signifies a success operation to one that
denotes the presentation of an information.

### Before
<img width="383" alt="Screenshot 2025-01-02 at 11 28 40"
src="https://github.com/user-attachments/assets/ff1df992-4f9c-4454-8dca-5a816c5ddf55"
/>


### After
<img width="353" alt="Screenshot 2025-01-02 at 11 20 11"
src="https://github.com/user-attachments/assets/f673edcc-ac07-4fdf-ba70-8491d75ffbe8"
/>



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packages/core/chrome/core-chrome-browser-internal/src/handle_system_colormode_change.test.ts

@@ -206,7 +206,7 @@ describe('handleSystemColorModeChange', () => {
           expect(notifications.toasts.addSuccess).not.toHaveBeenCalled();
           expect(type).toBe('change');
           cb({ matches: true } as any); // The system changed to dark mode
-          expect(notifications.toasts.addSuccess).toHaveBeenCalledWith(
+          expect(notifications.toasts.addInfo).toHaveBeenCalledWith(
             expect.objectContaining({
               text: expect.any(Function),
               title: 'System color mode updated',

packages/core/chrome/core-chrome-browser-internal/src/handle_system_colormode_change.tsx

@@ -103,7 +103,7 @@ export async function handleSystemColorModeChange({
       // we actually apply set the dark/light color mode of the page.
       currentDarkModeValue = isDarkMode;
     } else if (currentDarkModeValue !== isDarkMode) {
-      notifications.toasts.addSuccess(
+      notifications.toasts.addInfo(
         {
           title: i18n.translate('core.ui.chrome.appearanceChange.successNotificationTitle', {
             defaultMessage: 'System color mode updated',