Restore the style of the screen saver widget from switch style to

button style.

The operation of the Switch is not suitable for previewing the
screen saver and will make the user confused. So we change the
style of the screen saver widget back to the button style.

Fix: 189505023
Test: manually test the screen saver
Change-Id: I4a97d91cc0b76111d4cb7b6aa202f2207ee0ca5d