autoclick: Update panel theme when system theme is changed

Verified this change on DUT since the theme change still use the same
color token.
screencast: http://go/scrcast/NDY2NDk0ODcwNDY3Mzc5MnwyMzU5ZDc5Ni1kNQ

Bug: b/423936900 b/424517779
Test: atest AutoclickControllerTest, manually verified on DUT
Flag: com.android.server.accessibility.enable_autoclick_indicator
Change-Id: I7eca0d054f0509be8c8831400de6cbd0d6506906